I also work alone in an office for 3 years now. It's never been a problem. Some of the other professionals in my office suite work evenings and weekends, so there is often times people there during "off hours", but not all the time. I do most of my work by referral, but not always. I am careful not to accept new male clients too late in the evening. I always keep my cell phone and car keys handy, so that if I need to I can grab them and run. My husband always knows when I have a new client, especially a male, and he keeps and eye on the clock.
I think it's important to be careful what part of town your office is in and what other businesses are surrounding it. If you have a go-go bar on one side and a tattoo parlor on the other, you are most likely not going to be attracting your ideal clientele. And, as always, it is important to pay attention to the way your attire, your make-up, jewelry, visible tattoos, etc., as well as the decor in your office. It's important to have a professional and commanding attitude as well. Of course, you don't want to intimidate your client, but you do want to give the impression that you are in charge of the office. Yes, the session is to address their muscular issues and in that sense, they are in charge....but your professional and commanding attitude will help to deflect requests for "extras" and also cut down on the people who are going to ask for discounts, etc. With an "in charge" attitude, you will find that your clients will have more confidence in you and are likely to listen to your after care suggestions, as well as will rebook when you suggest it. It's all about confidence.