Here are some of the basic things to watch out for when joining an affiliate program:

No Affiliate Manager Contact Information
If they don`t provide you with a way to contact them about their affiliate program then what are you going to do if you have a problem? Who are you going to email or call if your check doesn`t arrive?

Commission Is To Low
Do you really want to spend time on an affiliate program that pays a measely 2%? I see these programs all over. They pitch their affiliate program and make it sound like it is a privelidge to join their affiliate program and earn pennies per sale. I usually stay away from programs that offer less than 8% commission. I will go a little lower if the products sell good and there is a good profit.

Unreasonable Cookie Length
Make sure you find this in their terms or information pages. This is the amount of time that the customer that clicks through your link remains yours. The standard cookie length is 30 days. This means that if your visitor clicks your affiliate link then they have 30 days to buy for you to get credit. You really don`t want to promote an affiliate program that offers less than a 30 day cookie length.

Merchant Site Has Traffic Leaks
Probably the most common thing I see with affiliate programs. Mostly from newbie merchants that just got their affiliate program started. Most don`t realize what they are doing and usually will correct the problem once I explain to them how traffic leaks are hurting their business and their affiliate program. Traffic leaks are links on the affiliate program site that potential customers can click on and go to other sites... sites that the affiliate won`t get credit for if the visitor buys something. Leaks can consist of third-party banner ads, Google AdSense ads, popups, popunders, text links, etc...

No Phone Sale Tracking
With the internet market growing so rapidly every year this means more customers are shopping online. Alot of them will call the merchants 800 number to call in their order instead of submitting it online. Where does this leave you? The merchant gets the cash on the sale while you get stiffed. So when evaluating an affiliate program be sure to check to see if the merchant has measures set up to track phone orders for affiliates. It is simple to set up and it puts the affiliates ID number next to the phone number. So when customers call in they are asked for that number so they can manually credit the appropriate affiliate for the sale.