I use artrage to give an oil painting feel to some details...not everywhere.
just in the large area. Indeed it's a bit hard to be really precise with artrage but you can ad some
paint effect and erase it later on photoshop. Like that you can combine two method for the rendering of your painting.
it's not a ultimate way, it's just my way and I found it to be really cool...but I'm sure you can find a lot of other method to give
the feeling that you want in your painting