Some of the factors you should consider.
1. Make money from the product ?
Don't be swayed just by high commission figures or multi-tier payments. You need positive answers to both these two questions
- Is it a product that people want and will buy ? Consider how it will fare alongside the competition.
- Is the commission rate sufficient to make your efforts worthwhile.
2. Effective sales page
Visit the sales page of the product to confirm that the sales copy does a good job of selling the product. Be aware of the various ways that can lose out on your commission. (These are explained in the following tip in this section.)
3. Affiliate support
The merchant should provide you with much more than just a link to join the affiliate program. Check for any useful promotional material - sample ads, articles, solo mailings, endorsements/reviews, signatures
Ideally there will be an affiliate mailing list so that the merchant can convey useful news. You want someone reliable who won't disband a program or make rule changes without telling you.
4. How many affiliate programs should you promote ?
If you plan to put a number of affiliate products on one page then the more you have the more diluted the effect. The exception being if they all relate to the same topic.
Otherwise if you keep them separate you can have as many as you like but do not underestimate the work involved for you on the administration side such as
- different procedures for signing up
- different ways of creating affiliate links
- different methods of payments, at different intervals
- handling ongoing communications from every program
A good compromise is to use a company which contains many affiliate programs under one umbrella. They consolidate your commissions into one payment and have a standardized format for affiliate links with no individual sign-ups required.
The most popular of these, handling digital products (ebooks, software), is ClickBank.
And here is an outstanding FREE tool which will let you search through the ClickBank Marketplace and see full information and ranking history for any product.