Everyone experiences different results with Affiliate Programs - however some programs are better than others.
You should settle on a theme for your site and then choose the best affiliate programs that suits this theme! Again, your experiences may differ to mine. My Top Ten Affiliate Programs have consistently shown excellent returns - however this is not the only criteria that I use in selecting these Top Ten Programs - the service they give to affiliates are first-rate, and this is a major component in their selection.
I also have an extensive list of Recommended Programs. I am not an affiliate of many of these programs, (because they don't fit the theme of my site!!), however I have compiled this list from user feedback and from scrutinising their terms and conditions and the service and support they give to affiliates.
Another type of program is the Two-tier affiliate program. They pay commissions on two levels and are definately worth checking out. The best ones are listed in my Top Ten as well as in my Recommended Programs area.
The advent of LifeLong Commissions has changed the Affiliate World. In particular, these are programs where you earn recurring commissions for life!
Other indicator's that you may find useful are Programs that have been voted for by visitors as well as on a click-through basis. You can find listings of these programs here:-
As with any program - before you join - read the conditions carefully and never hesitate to ASK QUESTIONS!