There are so many hitting/pitching coaches it is hard to know who is good and who is a waste of money. Above mentioned asking good teams coaches, that is a good idea. We have a local softball FB page where people talk about local instructors, maybe your area has one. I can also say that one sign of a good coach is how easy it is to get into see them, the good ones in our area have a waiting list. That is not the only way to tell but is a good indicator. The instructor we see is new to our area and gives lessons every day of the week. She went from a dozen clients to over 100 (not all of them see her every week) in less than 6 months, word of mouth spreads quickly.