This list is by no means exhaustive – it's really more the result of 1 a brain storming session when I sat down to figure out why some succeed online while others haven't succeeded. Yet. :-) You gotta sell something. I've known people who were "in business" for months, yet hadn't sold a thing. Until you start selling somebody's product (yours or someone else's, doesn't matter) you don't have a business.

Get into profit as fast as possible. If you're buying traffic, figure out how to make that traffic pay as soon as humanly possible. If you're outsourcing work, find a way to make that work more than pay for itself. Sure it's common sense, but I've seen a few folks go into serious debt.