It's a simple formula really. Direct traffic towards a funnel, which sorts and finds leads, which you then make an offer to. Provide an offer which has enough margin to cover your time and costs, and wal lah (I'm Texan not French :)) you've got profits.

Now just think of offers which are either evergreen, or so profitable now that you can't resist, and you'll enjoy Internet Marketing.

Promote dumb offers, get the formula wrong, forget what it's really about (lose focus),...