See your new user expereince with fresh eyes.
Sign up for your own site over and over and over. Watch others sign up for/use your site. It's gonna hurt, but you'll learn so much.
Get newcomers invested right away.
Do you really need to get users to give you all their information, letters of recommendation, and credit card before letting them use your product? How can you give them the experience of creating something they *want* to save?
Discover your "aha moment" and get to it quickly.
What is the most engaging aspect of your product? When do your customers cross a threshold of really really wanting to stick around? How can you provide that sooner?
Get small goals that expand into larger ones.
Games are great at giving people quests and achievements to level up on. Even (especially) if you're not a game, you can make it fun and easy to learn how to use your site.