Start off by joining the top affiliate networks. All of these networks are free to join, established and reputable.
TOP AFFILIATE NETWORKS
Commission Junction – Largest affiliate network for real products. Gain commissions from popular sites like Travelocity, Apple, Yahoo, and many more…
Linkshare – Top affiliate network associated with Walmart, ToysRUs, and many more…
ClickBank – Top affiliate network for digital products
PepperJam Network – Not as large as the 3 above but still contains good offers and are trusted
Amazon Associates Program – HIGHLY RECOMMENDED. Get a commission of every that Amazon.com sells. Any niche market that you will advertise to will have something that they can buy fro Amazon.com
Google Affiliate Network – Google is fairly new to the affiliate marketing scene though they are a big player. Their network is associated with many top merchants.