Where do I find the cheapest airfare from San Francisco to Hawaii?

If you don't travel very often I would look at sites such as Priceline, Expedia, Orbitz and Hotwire. If you do plan on traveling more often, I would look into learning some of the travel tips used by ex airline employees. There seem to be some known tactics that will allow you to get the same deals, if not better than the discount sites, just by knowing the proper times to book and the right things to say.