Something loose fitting, and good underwear.
I went for my lower back and hip and I was wearing a skirt and top, at first she tucked the skirt into it's own waistband and then I asked her if it would just be easier if I took it off.
For my upper back I wear a spaghetti strap vest top, and when I went for my knees it was a skirt or shorts (or really loose fitting pants that would roll up).
Wear good shoes as well, or they'll tell you off.