Drawing mandalas are a wonderful way to open up creatively as well as being a great way to induce relaxation. I often use them as meditation and to clear away creative blocks. I hope to, at some point, merge the mandala designs with my pottery vessels. I will be experimenting with that this summer.
There are many ways to "grow" a mandala but it nearly always starts with the "seed" - finding that center point and expanding the design outward. I find that the more I let the forms flow from stream of consciousness the more beneficial it is for me, creatively. Less planning, more flow. The process is just as meaningful as the end result.