I have not read the TOS, but from what I have heard, once you have about 10 articles you can start putting in like 1-2 affiliate links in there, just make sure to make them look non affiliate.
like instead of affiliatesite.com/?id=lucky13 make the link, yoursite.com/productname.html and do a redirect.
They use your keywords Themselves to point to other pages with higher paying content on them. If you look at your articles you can see the keyword highlighting, so they probably find the higher paying words and scan articles for them and then they get the cross linking on there own site and earn more from advertisers.