I would suggest that you read the Amazon affiliate contract carefully. I was a member for many years, but never earned much- my blog gets very modest traffic and my books of choice are not very popular, so even after several years in I only had a few dollars of earnings. You can't get paid until you've earned a certain amount- I forget what the threshold is now. It's either fifty or a hundred dollars. They just put in a new policy that if you don't make enough to get paid, you have to pay THEM $10 a month for maintaining your account! I backed out of the program at that point. Just letting you know.