Agree with Windriver. You should charge for your ground briefings. I do and so do all of my colleagues at the school where I work.
If you don't, all you will be motivated to do is to "get the Hobbs meter turning". As a new instructor, you may feel enthused and keen to provide lengthy free briefings, but don't worry, this philanthropy won't last long. If you want to eat, you'll learn how to maximise your income and become more mercenary.
Make sure that, when you do land-aways, you charge for the time spent on the ground. After all, you are still teaching.
It seems to me that the only thing you have to sell, as an instructor, is your knowledge. Don't give it away, it has cost you an arm and a leg.
Would you please enlarge on the "self-employed" bit, Nutloose?