I just started doing this on Aiesha yesterday - apparently, you should start seeing results after only a few sessions. Anyway, the idea is that brushing away the dead skin cells enables the skin to breathe more efficiently. It also stimulates the production of sebum which in turn improves the texture and tone of the skin.
Dry skin brushing also improves blood and lymph circulation by stimulating muscle contraction. The improved lymph flow causes more effient excretion of waste materials in the cells and interstitial fluids occurring in the spaces between organs and tissues. Clearing this area encourages more effient cell production and renewal.
If you're going to do this then use a natural bristle brush, a loofah, dry flannel or a mitt (goes without saying that you need to be starkers for this).Start at the feet and work up towards the top of the body using long strokes towards the heart as this helps the blood and lymph system work against gravity to return through the system. Apparently brushing away from the heart can cause faintness.
When brushing the stomach, use a gentle circular strokes in a clockwise direction to follow the flow of the intestines and not disrupt any bowel functions.
If anyone tries this let me know how you get on.

Best to all,