Hire the best people you can find. This was kind of easy in the early days of foursquare - we hired our friends who were really passionate about the stuff they were building. We have a superstar team not just because their resumes are so strong, but because they've been passionate, thinking about and tinkering in this space forever. Those are the people you want to surround yourself with.

Stop sketching and start building.

Forget about where you want to be and go out and build stuff. Dodgeball came from being bored at work... things happen because you make them happen. Stop sketching, and start building.

People can copy what you've done, but they can't copy what you still want to do.

If there's something you want to build, but the tech isn't there yet, just find the closest possible way to make it happen.

I keep a notebook in my pocket, and I write down all the stuff we could ever do with Foursquare.

I learned early on not to feel badly about reaching out for help, and not to feel embarrassed about saying that you're in over your head.