Your clinician can best tell you what you should bring on the day of the treatment. It’s generally recommended that you wash your hair on the morning of treatment (without applying conditioner). You may wish to come with your hair wet, combed out, and parted down the middle as that will speed up the process of putting on your cap.
You may also wish to bring your own warm blanket, socks, sweater, a neck pillow, etc. Some patients also prefer to bring their own towel as well, which is used when you are wetting your hair before putting on the cap.