Good question. I only sell packages and the reasons for that is simple. If anyone cancels their session in less than 24 hrs. before their appointment, then I charge them for that session (unless it’s an extreme situation). If they do monthly commitment then you run the risk of them either canceling, not showing up or even just fade away because they don’t have any real commitment in showing up. It becomes like a gym membership fee, where people get charge a monthly fee and they don’t feel obligated to show up. Also, by charging a monthly fee I believe you cheat yourself from some substantial income. If a client decides to come everyday of the week, then you will be making very little/session, where as if you charge them per session then you will be making what you think you worth (even if they train fewer times/week)…just my opinion.
Maybe you could offer both options. Some people might feel more comfortable paying a monthly fee and others buying a package or individual sessions. What ever you feel comfortable with, that is what you need to be doing.