I forget again who sent me this link, but I found CoffeeAndCelluloid's post on their KickStarter experience illuminating.
Although I have yet to engage in a crowdfunding attempt yet, I have been contemplating. And I have been providing some advice, thoughts, and general consulting to those that have. I think the points Joey Daoud raises about needing to raise a fan base first, having some investment pre-committed, and needing to have supporters, promoters, and blogs lined up in advance are all right on. He's helping all of us learn how to make this better together.
Joey also posted many good links to bring more perspective on the whole crowdfunding experience: