Ok so what I do. I normaly pick 3 colours, one light colour, one shadow colour and one that goes in between (for skin a more red colour etc). I draw where I get light and shadows. Then I normally pick 2 more colours for blending, and suck up and eyedrop alot along the way. I use a hard-edge round brush and for some parts sometimes a soft-edge round one. Then I keep my opacity at 100% and set my flow at ~15% for the first round blending and 1-5% for the more accurate blending. I continue this process till I'm ok with the result, then I make some more highlights with a very light colour and a higher flow (20-25%) to make some last highlights.
This method is works very nice for me, except for the fact that it sometimes looks a bit too blurry. So I'm very interested in how you work. Post away!