Site maps are helpful. The appearance should be clean - not cluttered. More than two frames on a page are usually a distraction - at least to me. If you use dark purple text against a black background, its going to be more difficult to read than black text on a white background. I'm not requiring color combinations.
Common sense is the key.
Misspelled words and poor grammar are detractions. Be sure to proofread your page. HTML HTML should be accurate. Strange symbols on a page don't help its appearance. LOAD TIME I like to see load times under 30 seconds.