There are a few internet millionaires out there that strive on nothing but the commissions they make from promoting other peoples products.
To do this you should have a clear picture of how everything works. The affiliate business works with you signing up to an affiliate network like clickbank.com and stat prmoting products.
There are a number of ways to do this. You can start by promoting a product on a topic you have some interest in. Just start by doing campaigns on it and get right into it. You can set up articles on Ezine Articles or Squidoo for some easy sales.