For building a large practice, not so much. I'm solo and will probably keep it that way. I make much more money than I need and enjoy my flexibility and free time, so probably not moving to expand out any time soon. But, some general rules apply, get to know the tax codes fairly well. It's all about knowing your overhead (rent, utilities, insurance, etc) for yourself and what that would be if you had employees as well (all of that stuff plus payroll taxes, employer contribution to healthcare plans, etc).