Hi Caroline, welcome to the community

You've found a wonderful resource of information, but even more than that there is this amazing network of fellow virtual assistants.
Make yourself at home and don't be shy about sharing your questions and comments on the boards.
As far as words of wisdom, my best advice is to treat your business as if it's already very much established. That is, if you plan on devoting 4 billable hours a day to clients, and 2 non-billable hours to your own business - start now, utilize ALL six hours (or however many it is for you), every weekday. Spend the time getting your contracts in order, creating policies, determining your target market, etc.
You'll be amazed at how far this approach will take you.
Wishing you much success!