One of the many advantages of starting a private practice today is that you do not have to invent anything. Pioneers have gone before you blazing a trail that may be difficult to follow but clearing a way for you that is much more convenient for you than it was for them.
For example, a private practice is a business, similar in many ways to a local coffee stand or an international company like Starbucks. Businesses of every size have to pay taxes. One of the best sources for tax information is the Internal Revenue Service. A private practice may be the first business that you have started, but they have seen many, and although their motives may be self-serving, they do offer help.
The United States Department of the Treasury has a website as well as printed materials. Their Publication 583 is entitled, “Starting a Business and Keeping Records.” You can find it at: https://www.irs.gov/pub/irs-pdf/p583.pdf
If you are ever overwhelmed by the technicalities of starting your private practice, then recruit local help from your CPA, attorney or bookkeeper (who already uses QuickBooks and knows from other businesses how to help you start yours).
If I can help you with the scary parts, then I would work with you through the course that I taught on Private Practice Pragmatics at Whitworth University. Contact me at https://drraysmith.com/.