OK, I'm at a loss.  I've been trying to find some good tutorials that will help me learn how to paint over photos and renders to get a painted look, for portraits in particular. 

 

There are a load of artists over at DA that do this method, but it seems not one of them has produced a tutorial.  To give you an idea of the sort of things I want to do, take a look at the gallery of this artist: http://elenadudina.deviantart.com/