SEO is the key. It will take some time, but well worth it. You do not need a large site, you just need to optimize each and every page for your keyword terms.
Narrow your focus down and get as much relevant content as possible (without copying or rewording it from another site). If you are in need of content and can’t afford to pay someone then ask a few affiliate mangers to get you some.
Read the Google webmaster forum for information to be sure that you are following all of their rules. Find a SEO tutorial site and then get a tool to help with SEO and pay attention to the keyword density and use clean code on your site.
I’ve never participated in link exchanges or bought any traffic.