1. Only promote quality websites. Your reputation is on the line also.
2. Provide honest information
3. Don't try to "sell" the website. Provide honest information and link to content relevant to that information
4. Banners don't work as well as quality information pages
5. The majority of the text content should be your own

Affiliate Marketers Handbook - A complete guide to affiliate marketing that is considered the best in the industry. It includes audio lessons, weekly updates, and a bunch of valuable web tools.

Web Position Gold - This tool allows you to see where your site ranks with all the search engines for words or phrases related to your site. It will also analyze the top ranking sites for each phrase and compare them to your own site and make recommendations on optimizing your site. You can download the free trial here.

Word Tracker is the best program for choosing the right keywords and key phrases for your site. They have a free version that will give you an idea how their program works, and the paid service starts at $6.00. We use their service every time we build and optimize a new page.

Like almost every other affiliate program, I've made most of my sales when providing quality information and then simply linking to related products within the article itself. Banners do create some sales, but at a much lower percentage than the information pages.