GREAT TIPS Paul!!!
Newbies should realize that some of the highest traffic sites and some of the highest earning affiliate sites are very simple.
One affiliate site example I can share, because it's public knowledge is
Plenty of Fish. It's one of the simplest dating sites out there and it's free. I don't think the design is even that nice and it's been noted it's one of the ugliest money making sites.
Markus makes $5 - $10 Million a year with this site!
Not saying to make UGLY sites on purpose. Just showing it does not have to be flashy. (although I know a couple affiliates who do make ugly sites specifically because they think they convert better.)
However even if using a simple design, affiliate sites should be clean with high usability - ie, as Paul said, product pictures, obvious links (blue underlined.) Flashing banners, scrolling text and other types of stuff that may look cool on a Myspace page will just distract from the purpose of an affiliate site.