I'm slowly finishing this piece. It's very difficult to find a balance between beautiful rendering and keeping it alive, spontanuous.
Personally I'm a big fan Of Frans Hals, a dutch master from the seventeenth century.
I went to the Frans Hals Museum in Haarlem a couple of years ago and it struck me that all his models were looking so intense but also very relaxed in the 'camera'. It was as if they had been posing for just a few minutes, and the master had painted them in just a second.