Your clothing is an important pre-interview consideration. The basic rule is to wear nothing that will attract attention to itself or detract from your message. Keep it simple, tasteful, and appropriate. Neither overdress nor underdress. If convention or local tradition calls for you to be in shirt-sleeves instead of a jacket, or in slacks instead of a skirt, do what you feel is right.
Subdued shades of gray or blue, ranging the full spectrum from light to dark shades are appropriate on television, with pastel shades in shirts and blouses. Light colors tend to cause the automatic irises in the cameras to overcompensate, so white shirts and blouses are not a good idea. Burgundy ties and scarves are especially good because, regardless of skin tone, they add a desirable, healthy look to the face. A word of caution: don’t wear either brand-new or “worn” clothing. Men should not get a new haircut within three days before going on TV. If you'll be appearing in front of a green screen, don't wear shades of green - otherwise, your body will appear invisible to viewers!
It is generally better to wear long sleeves on television than short sleeves, even in summer – whether you are wearing a jacket or not. Skirts should be long enough to cover the space between the cuffs and the top of the socks.
Neither men nor women should wear vests on television. They enclose the body like a sausage casing, cut off circulation, tend to make people look heavier, and contain body heat. Neckties should be tied a bit shorter than usual for television appearances in which the guest will be seated. Otherwise, the length of the tie extends below the belt when in a seated position and will look distortedly long. Avoid patterns, checks, and stripes that might make the image on the TV screen appear wavy, or look as though it is “buzzing.” This is a moiré effect that is caused when the dot matrix of the TV crosses with the pattern of clothing. (You can get the same effect by crossing two window screens at various angles and looking through them into the daylight.)
All clothing should be lightweight, even in winter, for all television appearances. It gets under the lights, and stress adds to the problem. Should you be wearing a necktie and you feel overly warm, unbutton your top shirt button and then slide the tie back in place. The adjustment will never be noticed by the audience – certainly not as much as perspiration might be.
Speaking of perspiration, if you get hot under the lights – and some studios are poorly air-conditioned – a crew member may “mop” you during breaks if you request it. During an outside interview of any duration in the sun, you may also ask to be “mopped.” If the outdoor interview is being taped, there may be opportunities between takes for “mopping.”
Source for this material: The Executive Television Workshop, Inc., 36 West 44 St., New York, NY 10036