Big-screen TVs can collect dust, fingerprints and other smudges, so you need to clean it off regularly to prevent the dust from damaging the TV. Because older, CRT TV screens were made of thick glass, wiping away dust and smudges strongly would not cause many problems. Because today's big-screen TVs use LCD or plasma screens, you need to be more careful with cleaning because the screens can be damaged more easily. You also need to make sure no cleaning liquids seep inside to the internal components.
Cleaning a big-TV screen without any liquids or sprays is best, using simply a cloth to wipe away fingerprints and dust. If you must use an aerosol or liquid cleaner, look for a commercial cleaner designed especially for TV screens; an electronics store may be just as good a place to find them as a home improvement store. Gel-based cleaners are best, because they are less likely to seep down into the TV. Lukewarm water can also work; if you have to use soap (for wiping away something a child got on the screen, such as crayon marks or chocolate), make sure it is a mild soap. You shouldn't use Pledge, 409 or other cleaners with strong chemicals on TVs or any other electronic devices.
Use as soft a cloth as you can find for the thin LCD/plasma screen. If you purchased a commercial cleaner designed for cleaning a TV screen, it will usually come with a cloth also designed to use on such screens. A soft terrycloth towel, microfiber cloth or chamois will work. (Chamois cloths are often used in car care; make sure you use a fresh cloth that has never been used on a car.) Using newspaper, paper towels or any paper product made from wood is not recommended, because they can scratch the screen.
Unplug the TV and disconnect all other devices, such as a cable box or DVD player, from it. Not only does this remove the electrocution risk, but it will also make smudges, dust and prints easier to see. If you use water or a solution, apply it to the cloth--not directly to the screen. The cloth needs to be only dampened. Wipe the screen softly to avoid any damage that vigorous rubbing can cause. Go from one end of the screen to the other in a single stroke to keep the number of strokes to a minimum. If any residue is left on the screen (such as from soap), wipe it away with a fresh, dry cloth of the same type.