How to succeed with an Affiliate Program?

There are many thousands of affiliate programs you can join. Yet to succeed you must a subject area and stick to it. It is necessary to do somme affiliate marketing research by reading as many articles on a subject as possible. Pick an area that you are interested at and know something about (for this purpose, you can see articles related to 'How to find a good niche and keywords').
Then pick, for example, 3 affiliate programs in this subject/niche. This way you will force youreself to concentrate on fewer areas and fewer affiliate programs.
If you focus and find your own niche you stand a much better chance of making decent money with affiliate programs.