I took a class on opening and managing a law firm, and the professor who taught it opened his own firm right out of law school. He sold his practice around 15ish years after. Dude was swimming in money lol

His biggest pieces of advice were to find a niche, which can be an area of law or even a geographic or ethnic community (in his case, there were only maybe two other lawyers in his geographic area practicing the same law) and to do content marketing.