Now that Photoshop and programs like Painter are so advanced, you can pretty much paint a picture and it probably would freak people out how close it can look like oils on canvas. I usually swapp back and forth with both programs.
Usually digital painters will start off with a basic layout on a grey background using an angle black brush just to get an idea of how they want the overall image to look like. It's really rough and usually takes 30 - 60 minutes. From there we detail it out with again, using just a black brush and often use the eraser tool to take out unwanted paint. When we have everything done in black and grey, we begin using a light grey to white brush and start gouging highlights here and there to pop out the image. We keep doing this until it takes a 3D form.
From there we usually use a multiple and overlay layers to bring out some color then add a final layer for special FX like smoke, lighting, fire, gleams, rain lightning etc. most people are like... uhmm.. I dont get it!! Once you understand the basics of Photoshop, you will understand the terms - so get on it!! :D
I personally love oil painting, but it takes FOREVER to do. So, digital painting is a great way to meet a clients deadline crunch. Specially for video game and film work. NE how, just thought I'd throw this up here since people have been requesting for this info. :) Below is just a design I did of an anime style character - I love illustrating these one shot characters, totally fun. Enjoy! -- and I hope the mini tutorial upstairs helped in some way or form. ;)
Pat Lee