1. They are persistent.
2. They network.
3. They listen to feedback, even if they don't like it and choose not to act on it.
4. They have a clear idea of which market or genre they are aiming at and what the requirements are for it.
5. They work hard.
The truth is, to go from unpublished to published your work has to be better than anything else that is out there. Above average isn't good enough, it has to be exceptional.