In particular, black text on white backgrounds should be avoided. Light-colored text on dark backgrounds works the best. Thin lines look wavy on a TV screen, so you will need to fatten up all of your thin lines and images. Horizontal rules that are one pixel thick will flicker. Keep all rules at least 2 pixels thick.
People are even less inclined to read on a TV screen than on a computer monitor.
It's best to long paragraphs into a single sentence. Convert your image colors into WebTV friendly ones. This will make a big difference in your images appearance. The easiest way is to use and run your images through Photoshop's NTSC filter. NTSC are the standards set by the National Television Standards Committee.