A big event like the World Cup 2010 is just the kind of excuse that some of us are looking for to finally ditch that creaking tube opposite your sofa and splash out on a shiny, new flatscreen. After all, we all deserve a bit of decadence every now and then.

The problem is that buying a TV can be a pretty daunting task particularly as it's a major purchase both in terms of the cost and the 5-10 years or so that you'll probably be stuck with it. So, to make sure you don't end up making a decision you're going to regret, here are a few dos and don'ts of buying a new TV.

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DON'T just buy a Full HD (1080p) TV because it is the highest resolution
Resolution is all about the number of pixels that you have making up the detail on your screen and so the more there are, the better the quality of that picture is. Now that's all very well on a medium size TV and the larger you go the more important it's going to be. However, if you're buying a set the size of a postage stamp, then you're not going to be able to appreciate all that extra detail, so rather than waste money on going for 1080p, you might do better to take a step down to 720p and spend the extra on better functionality or design elsewhere in the set.

DON'T confuse 1080p with 1080i
There aren't so many 1080i sets sold any more, but if you're buying something second hand, or just picking up an older model, then don't be fooled into thinking that these two standards are the same. A 1080i set is actually only going to have half the number of pixels on the screen at any one time that a 1080p set has and is arguably a worse choice than a 720p resolution TV. For the best, most succinct explanation of the difference watch this video but, just to confuse matters further, most of the HDTV signals you'll be getting are only in 1080i anyway, so it's only really with gaming, Blu-rays and the odd downloaded 1080p video that you'd be missing out. Still, it's only a matter of time before the state of things improves on that front. On the whole, we wouldn't recommend 1080i.

DON'T just buy the biggest screen you can afford
Naturally, our first instincts with TVs are that bigger is better. In some ways it is, but in most it just isn't. Firstly, a bigger panel size is going to cost you more, meaning that for the same money you could buy something smaller but better quality. The other issue is that there's no point in getting a 60-inch TV if you're only going to sit 1 metre away from it. Watching too close is not good for the viewing experience, so make sure you choose the right TV size for you. Measure the distance between where you're going to sit and where you want your TV and then consult this page for a decent idea of what panel size is the one you need.

DON'T believe all they say about contrast
Contrast is probably the most important factor of picture quality and it represents the difference between the brightest any one pixel can be at any one time compared to the level of blackness another pixel on the same frame can attain. The bigger the difference, the deeper the colour palate can be and so, the better your picture. You'll find it expressed as a ratio of some very large number to one, eg: 20,000:1. The problem is that this is often the dynamic contrast rather than the true contrast and that's not quite the same. So, don't be fooled by the numbers but, that said, they're not always lying to you either.

DON'T buy a 50Hz TV
All TV signals, certainly in the UK, are at frame rates of 50Hz, but what a lot of modern sets do is use technology to effectively double or quadruple this to an approximate version of either 100Hz or 200Hz and there are even some 400Hz sets on the horizon too. Because these TVs refresh the series of static pictures much faster, the upshot is that you get a smoother experience when watching fast action video. If you just go for a 50Hz option then you might find you get a juddery look which you'll often see on poor quality pub TVs where you can barely follow the ball as it's passed between two players in football. So, if you're buying your set for the World Cup, you're a sports fan or you're planning on watching lots of action films, then make sure you spend the extra on a flatscreen with a decent refresh rate.

DON'T buy a TV with a response rate greater than 5ms
Response rates have been usually less well advertised at point of sale, but they're increasingly coming to the forefront. They correspond to the amount of time it takes your pixels to change from one state of brightness and colour to another. If this time is slow, ie greater than 5ms, then you're going to start noticing strange after effects on the picture like judder and blur. As your refresh rate goes up it becomes more important to make sure that you've got a good response time to match.

DON'T pay any attention to the speakers
On the whole, the speakers in modern TVs are absolutely rubbish, so just ignore all the specs and sales talk about them. The trouble with a flat panel is that it simply can't offer the cabinet room for decent sound to come from. Your old CRT will probably deliver better audio for you. What you really need to do is ignore the built-in speakers and just buy a sound system separately.

DON'T forget about your connections
Make sure to stick your head around the back of the set or at least ask what each TV has in the way of connectivity. You'll want at least 3 HDMI ports really and Ethernet and audio inputs as well. Not all TVs are going to be internet connectible and, although it's not vital given the kind of widget support at the moment, being able to get online with your big screen is going to be a real bonus soon. If it's got Wi-Fi and USB support, then so much the better and it's worth keeping an eye out for DLNA so that you can wirelessly stream over media from your computer and other devices.

DON'T worry too much about built-in tuners
Having a Freesat or Freeview HD tuner built in is a great thing, especially with the World Cup being broadcast in HD, but it's not everything. If you have a Sky or Virgin package anyway, then you'll be getting all your programming through their set top boxes anyway without the need for these other tuners. Even if you don't you can always pick up cheap models to plug in externally or something fancy with a PVR as well.

DON'T just look at the TV straight on
You might have your own chair in prime position when you get home, but there will be some of your family and friends looking at the TV from a bit of an angle. Most of the time, this is going to be okay but certainly with older sets there has been a problem with losing picture quality as the angle gets more acute. A quick side step to the left should be all it takes to cross this one off the list.

DON'T be afraid to buy online
You can get some excellent deals buying TVs online. One of the reasons they're cheap is that many of these sites don't have overheads like some of the larger stores, so don't worry too much if the cheapest offer appears to be from a shop that you've never heard of. You are protected when buying online, particularly if you make your purchase with a credit card and you always have the right to return things even if the vendor starts to blame the couriers. Not your problem and not your fault.

DON'T listen to anyone else's opinion on 3D
3D is here to stay on TVs. Now that both Hollywood, Blu-ray and Sky (in the UK) has got hold of it, don't expect this format to disappear in a hurry. Now that doesn't mean you need to bother with it if you don't want to. You're not going to have a bunch of doors shut in your face if you don't. If you've been to the cinema and the 3D effect is something that excites you, then by all means, go for it. There's plenty of content on its way especially in movies and sport. It doesn't come cheap at the moment but it's not crazy expensive either. It will require you to wear glasses but don't let that put you off. If you like 3D, then it won't be a drag. No one cares how silly you look; not in the comfort of your own home.

DON'T be afraid to negotiate
This is a big purchase you're about to make and the shop is about to make a big sale as well, so there's probably some room for negotiation here, and, even if there's not, it's worth a shot. You might not be able to get any money off the ticket value, but there's every chance they'll be able to throw in some HDMI cables, free delivery, a Blu-ray or two or even offer a discount on another product such as a Freeview HD tuner or PVR. Don't be embarrassed and British. Be bold as brass. It's always worth a go.

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DO measure your lounge
There's no point in buying a 50-inch TV if it's not going to fit in that alcove where you intend to put it. Save yourself some headaches and measure the space where you want it to go to help work out what's the maximum size TV you can buy. While you're there, measure your viewing distance to help get the right panel as well.

DO appreciate the difference between LCD, LED and Plasma TVs
5 years ago, everyone would tell you that plasma is where it's at for the highest quality, but owing to the huge investment in LCD and LED technology, it's not so cut and dry any more. Classically, plasmas offer higher refresh rates, more natural colours and better contrasts whereas LCDs give punchier pictures and more bang for your buck. Plasma screens are also going to use up a lot more power to run.

More recently, there have been developments in LCD technology to produce LED TVs which are essentially the same creatures, but where the backlighting is provided in a more precise manner with a series of LEDs rather than clumsier fluorescent tubing. They're more expensive than normal LCDs, but can give far better contrast, colours and response speeds as well as being much thinner. The slightly lower end of LED TVs are the edge-lit models whereas the LED backlit or "Full LED" TVs will deliver better results. If you've got money to burn, then it's probably still worth heading for a top-end plasma (or even an OLED) otherwise it's an LED if you can afford it or a straight LCD if you can't.

DO set a budget for yourself
It's very easy to be upsold when buying a TV, largely because we all want to buy the best one we possibly can. There's such a large number of features and functions that it's very easy to get carried away, so make sure you've set yourself a limit and try to leave some cash for a decent sound system and maybe the odd meal every now and then. Once you've done that, go down the shop and, when tempted, add 15 per cent. You only live once.

DO read the reviews
All the specs and features are one thing but what makes a TV good is something a little less tangible than that. Sometimes all the processing and technology can come together to come up with a picture that's actually quite flawed. On top of that, TV reviewers will have spent a good few weeks with each model and will have picked up on things like usability and anything else that you might miss in the show room. So, whether it's in store at the point of purchase or entirely premeditated research, make sure you read the reviews. There's a stock of our very own just here but do scour the Web for second and third opinions.

DO judge the picture for yourself
By the same token, don't buy a TV just because someone else tells you it's good - whether that be a salesman or a reviewer. At the end of the day, it's your TV for your living room and your eyes. You might find that the way some sets present their images just jars with what you like. Probably the best thing to do is to read the reviews and go in with a short list of a few sets you're interested in and see which one works best for you once you've put them through your own tests. Your brain will tell you which feels most like home.

DO look out for jagged edges on the picture
Some sets tend to have so much technology going on that they tend to over process the pictures. The end result can often be strange, unnatural looking outlines to objects on the screen or sometimes ripples and artefacts around the edge of the frame during panning and motion shots. Just keep your eyes out for this kind of thing. If you don't spot it now, you can bet you'll never be able to shake it from your mind after having it at home for a couple of weeks.

DO ask for the remote
There's two reasons to do this in the show room. The first is because you want to know if the TV is easy and intuitive to use. The second is to make sure the sales staff haven't jacked the contrast and brightness all the way up to make the picture appear better than it actually is.

DO take in your own media
It's no good judging a TV by watching cartoons or the sample footage from the manufacturer. They just won't show up the issues that the set has. If you can face it, take along a DVD to see how it copes with standard definition video and a Blu-ray to judge the HD processing as well. If you watch a lot of sport, then take along some footage of that and you'll probably get a good idea of how well the TV copes with fast action too.

DO check out the black levels
There's nothing more annoying than not being able to tell the shadows from the details in dark scenes and it's a classic problem with lower end LCD sets which often suffer from light spill from their backlighting systems. Take along something like The Dark Knight or other moody footage to get a better idea of how well the set can cope here. You might also want to check the brightness setting on the TV while you're at it.

DO take note of the ambient lighting
A lot of TVs might look really good in very dark rooms with no light to compete with but that's not very likely the way you're going to be viewing them at home. Just take note of the amount of ambient light around the TV you're testing out in the show room so as not to be disappointed when it looks very different after you've bought it. You also want to keep an eye on if the glass panel causes any nasty reflections as well.

DO look out for bargains
The brand new, latest TVs on the market are not necessarily the best. They might offer more advanced functionality but not the best picture, so by all means keep 'em peeled for last season's slightly older models that are up for special offers. Shops like Richer Sounds are great for picking up a bargain as they'll quite often slash prices on perfectly good TVs just to get rid of the last few models, while making shelf space for the latest batch. On top of that, stay alert for special promotions such as the glut of World Cup offers doing the rounds at the moment. 

DO be prepared to compromise
It's easy to sit here and bang on about all these things you need to look out for in your new set, but the fact is that if you stuck rigidly to each, you'd probably end up spending £2000 and most people just don't have that kind of money to burn. Compromise is the watch word here. Pick three or four areas where you're willing to be flexible and don't rule out a really good TV just because you want a bigger one or it won't wirelessly feed your dog. At the end of the day, a TV's job is to provide a good picture, so it's here you should probably stick to your guns and let the rest go to the wall.

DO recycle your old TV
A lot of places will dispose of your old set as a matter of course when they deliver your new one, so make sure you ask if they provide this service. If not, then do the responsible thing and take it down to your local recycling plant.

Good luck and happy shopping.