I've been asked before how I do my interiors, so since I happened to take a lot of in-progress shots of Synnaquin's Lair and had my sketches still around, I threw together a tutorial. These are the basic steps I use to put together a complicated painting like this one was, and can really be applied to any scene you'd like to paint. It doesn't have many tips on painting or drawing or Photoshop, but there's lots of tutorials around there to help with those!
I intend to do a tutorial on perspective sometime, but this at least gives some ideas how I put it to use.
Sorry it's so big but I had lots to say!
Here is the final painting: