In a Bodymind Bodywork (or Ball-Asana) practice, we combine gentle asana (yoga poses) with muscle and soft tissue release techniques. What do you need to know? That it's like giving yourself a massage using your own body weight and gravity, on the floor or at a wall. Self-massage techniques can lead to a greater understanding of how your muscles work to move your bones. They can also help to release tension and emotional "knots" you might be carrying.
The techniques I have studied range from small ball release techniques such as body rolling, the miracle ball method, kinetic awareness, and bodymind ballwork to other forms of myofascial release therepy like trigger point therapy and the melt method. We use rubber balls and inflatable balls ranging in size from 1" up to about 10". (I belieive they're more effective than a hollow ball, and there is a method.) In a private session, I also use techniques that I learned in Thai Yoga Therapy and Yoga Therapy training.
Disclaimer: No self-treatment technique should be considered a replacement for body work with a qualified professional. It is possible, when using this kind of treatment on your own, to cause more constriction than release (please take a look at this article from Elephant Journal). For example, rolling your foot on a tennis ball can be a good thing. I believe that it's beneficial to have some knowledge of the anatomy of a foot, what might be causing your pain, and what could be an effective way to relieve it. While you may feel occasional therapeutic discomfort, severe pain is an indicator that you may have overdone it.
I used my method to break up scar tissue and adhesions after hip replacement surgery. Of course, I had the go-ahead from my surgeon before bearing weight on top of a ball around the surgical site. I had pictures so that I knew he would understand exactly my intention. I also take advantage of the services of professional massage therapists on a regular basis.