Succeeding In Crowdfunding Campaigns

I have seen that Crowdfunding is one way to get a money injection into your product or intended service. I have checked Kickstarter and Indiegogo as places where the crowdfunding people are going to. I know that you have to create a demand for your "product", but I have not done any crowdfunding campaigns before.

Has anyone done one? Did you succeed? What were the things you did that contributed to the success of your campaign?