I’ve discussed a few strategies with other affiliate marketers over the years on how to create a backlink network for your sites. This is also heavily discussed and described well at Wealthy Affiliate.
The goal is to drive organic traffic to your ‘money site’ by improving your page rank score via backlinks. I personally like to drive traffic with a combination of organic and PPC traffic and not restrict myself to one or the other. The down side to this, is it can be difficult to fully see what’s working for you. If you’re doing PPC, you’ll want to be sure you’re capturing keywords somehow. By doing so, you’ll have a better grasp of how traffic is getting there and most importantly, what traffic is converting.