*Be careful of who you recommend on your affiliate site because if the services and/or products they offer aren't satisfactory to consumers, you'll look bad as well.
Once you've found an affiliate program directory that is well organized and current, search through the listings for related affiliate programs. Check out each of the web sites and make sure they are well designed, have good navigation, and seem to inspire a level of trust. If you do not know the company and have never heard of them, make a purchase from them and see how well the order is fulfilled and verify the quality of the product (you will be recommending them when you launch an affiliate program). You'll lose credibility with your site visitors if they have a bad experience with a merchant you recommended.