I think that if you could build up your traffic and an interested follower base, then you can offer access to that base to others would would want to advertise to them. If you have followers who trust you and would take your advice, they are liable to support an advertiser that you choose to promote.
Generally you want to advertise products that are related to the topic of your site. If your site is about motorcycles, you could sign up as an affiliate for a site that sells gear or clothing.
Ideally you'll promote products that your visitors are interested in. There's a process for finding out what your demographic is, but guessing is sometimes just as good. You can go general, like everyone that visits your site is probably interested in food, or money, or television, and they probably wear clothes; You can go specific like visitors to a site for new moms are probably interested in stuff having to do with newborn babies. And if you can find a product that pays repeatedly, that's even better. The more work you do to match your advertisers to your visitors, them more money you'll make. Track your results, keeps what works, eliminate what doesn't.
Also, in my experience managing sites purely for ad revenue, ppc sites don't pay all that well. You can use Google's external PPC tool to figure out how much money you'll probably make. Eighteen cents a day doesn't pay the bills. When I first started I was making six dollars a week. I got that up to $250 with no increase in traffic. It's worth it if you work at it.