I've also decided I would like to paint into photoshop in a similar way I would paint with oils. I did this quick sketch just to see what it was like - it was more fun than I was expecting. I kept the brush to 100% opacity and just thought about tone and colour. I tended not to use glazes when painting - I prefer the direct method. No soft blending, just finding the tone in the middle and putting that down (I think this is much harder when painting from life, so its a bit of a cheat here). I'll call it 'Grumpy Face', whenever I paint faces from my head they turn out this way - probably due to a lack of study of expression! Maybe I'll put that on the list of things to do too, paint faces form imagination that have a more interesting expression. Anyway as an exercise it was quite enjoyable and something I'm going to continue with.