Advertising on Facebook

So I've taken a look at Facebook's advertising thing. It's quite easy to manage, and my target market is so small, it's actually quite affordable for me as well! I'm thinking about taking the plunge and seeing what sort of response I can get from Facebook Advertising - and since I've stopped advertising with shopping.com, I've got cash alotted to advertising anyway.

If anyone has any good tips for advertising on Facebook, I'd love to hear them!