I am just starting out but as I am planning the three that come to mind that I feel are going to be most important for my success are:
1. Signed contract (I know from being in the corporate world how important this is. It avoids any misunderstandings later)
2. Once I nail down my billing policy I am going to stick to it so that the client expects it when it is due and it isn't just something I do when I get to it.
3. I am going to try for no work or limited work on the weekends. This is my time with my family and that is very important to maintain a happy household.

Thanks for posting the question Tess.

Amy