It's a truism in audio that it doesn't really matter what the rest of the equipment is like, if your speakers are lousy, the whole system will be lousy. The same holds true in video: the best ancillary gear in the world won't make up for a TV monitor with a bad, or inappropriate, picture.

So selecting the TV that will work best in your situation should be done with some care. This is especially true in a larger setup, such as a home theater, because the television is likely to eat up a considerable chunk of your budget.

Things have become more complicated recently with the advent of high-definition television (HDTV) and other digital formats, but given the snail's pace of the rollout of the new media, it's safe to assume that most buyers are still looking for analog sets. We'll tackle digital separately in the future.

The first task is to decide how the set will be used, and pick one that is suitable. If it's meant to be a bedroom TV that will let you drift off with the late movie playing, there's little point in buying one with sophisticated inputs and outputs, but a sleep timer -- or at least an infrared remote -- is a must. If, on the other hand, the set will be the centerpiece of an elaborate audio/video system, it had better have sufficient connections for all your other gear.

Once such basic questions are out of the way, the first thing to determine is how big a screen you will need. Sizes range from a diagonal measurement of 13 inches to something like ten feet, and what will be right for you will be determined by the nature of your viewing room and of your viewing habits. If you watch mostly movies -- especially widescreen versions -- you'll probably be more satisfied with a larger screen, while talk shows and news programs can seem a bit overwhelming if the images are huge. Small rooms don't take kindly to monstrous sets, and small screens get lost in large spaces.

There are no real rules, but if your viewing seat is 10 to 12 feet from the screen, you should be looking in the 29-to-35 inch range.

The size will also tend to determine the sort of display you buy. Up to about 35 inches, sets are convention direct-view cathode-ray tube (CRT) sets; above that they are projection units that use bright tubes that cast the image on a screen using lenses. Alternatives are the flat-screen sets that use liquid crystal displays (LCDs), plasma, or digital light processing (DLP). These can offer impressive performance, but usually at enormous cost.

Of paramount importance is picture quality, and you may find, for instance, that you prefer a slightly undersized CRT model to a more appropriately scaled projection unit, because it has a better picture.

Picture quality is not always easy to judge in a store. For one thing, the factory setting of most sets are cranked specifically to make a dramatic impression on the sales floor. Also, you have no idea what adjustments the customer before you may have made to the set. With any monitor you are considering, insist that the dealer give you the remote control, and then try to adjust for the best possible picture. Use something familiar -- local news is good, or a familiar soap -- and try to get the most natural image. If you can't achieve something you like, move on.

This exercise will demonstrate something else. Remote controls, and the on-screen menus associated with them, vary widely: some are easy and intuitive, some will drive you nuts. This exercise will effectively demonstrate whether the controls are friendly or not.

Another thing to consider is the set's audio quality -- again something that's not easy to judge in a store. If you intend to have the set hooked permanently to an audio system in a home theater environment, perhaps the onboard audio is not all that important. But many viewers don't bother with the full A/V system when just watching the news, so if you expect to want to listen to the internal audio at least occasionally, make sure its sound is acceptable.

In addition to checking for the right number of inputs and outputs, give some consideration to the tuner. All sets will tune the regular VHF and UHF bands, and most nowadays can be set to tune in the specifically cable frequencies without a converter. If you're on cable, make sure the set will do that.

A useful amenity is the ability to program in the channels you commonly watch so that you can click from one to the next without having to stop on unwanted or empty channels. There is usually a limit to the number of channels you can program, so make sure there are enough.

Once you have made the buying choice, and have unpacked your new set at home, it's time to set it up so it will give its best performance.

First, you have to put it somewhere. In many rooms, the positioning options are fairly limited, especially for a large set, but there are certain things you should avoid. The set should not be put in a position where the sunlight falls directly on it during any part of the day you're likely to be watching; if the screen is washed out by the sun at three in the afternoon, you're going to miss some football action. By the same token, make sure there are no windows or lamps reflected in the screen when you are sitting in one of the primary viewing seats.

Have a look at the lighting in the room, not just the positioning but the amount. TV is not meant to be watched in a brightly lit space, so consider turning lights off or using lower-wattage bulbs to give the room a soft glow. It shouldn't be so dark that you can't read the TV listings, but you shouldn't be able to perform surgery either.

Finally, adjust the set itself. There are test discs that let you do this with some accuracy, but it can also be eyeballed fairly effectively. First, the picture is almost certainly too bright, so the initial action is to turn that down; make it look a little too dark, and then watch it for a while to get used to it. Some judicious fiddling of the brightness and contrast should yield blacks that are really black and whites that don't bloom or turn blue.

If one of your available channels broadcasts color bars, use them to get the color level and tint right. First look at the red bar and adjust the color level so its bright but doesn't slop over into its neighbors' bands. When that's right, adjust tint until the yellow is a true lemon yellow, not orange or green. Then check these settings on a known program -- again local live news is usually good -- and make sure the skin tones are right. Then, if your set lets you do it, save your settings so you can return to them if someone else fiddles with the controls.