I used several different types of income streams, let me break them down to you and explain how each of them works.
Affiliate - This is basically getting a person to sign up for another web site. Once they do, you then receive compensation for it. These can be either free sites to sign up for or sites that require you to pay to signup. Remember you do not always need to go for a big sale, a lot of commissions from free sites add up quickly.
There are lots of Affiliate companies out there, it is easy to google for one and just sign up to be a publisher.