I know a lot of artists use this technique, but I learned it from Donato Giancola. Although I am not really "into" fantasy art, I think he is probably one of my favorite artists; he is amazingly talented, successful, and really nice guy. So here are the steps I took.
Drawing: I drew the picture on Reeves paper (it's nice and soft and erases pretty easily)
Next, I made a photo copy of my drawing onto Mi Tientes toned paper. I then used mat gel medium and mounted it to my piece of board. Then, I painted a value layer with acrylic
Done! I finished it off with oil paint!