1. Lots of Hubs that are well-written, informative, and that appeal to a wide range of people.
2. Networking by linking to other sites and by talking to other writers and hubber.
3. Limitless patience. I've been here over two years and am not making much at all.
4. Stubborn optimism!
and of course, make sure under your affiliate settings-earnings page that you have all the necessary things activated (google adsense, hubpage ad program, etc.)