Though all four strategies are good but you forget to mention social traffic. SMO can be the great source of traffic these days. I am getting most of the traffic from Facebook, Twitter, Stumbleupon, Google Plus, Pinterest ..
and also you can use URL shortening services (http://q.gs/5dfC8) that pays users for each click they received on their short URLs.
Seriously very good information. In fact, the whole reply section itself is very interesting and it gave me a whole lot of information. I am new to affiliate marketing, and still learning ways to do it by reading DP threads.