It's been awhile, and now I have sketches available on my site, so I'll break down the current crop in this post. Links go to the full piece, but I've included some detail shots for ya here to break up the usuall Wall of Text.
Planar Standoff: When composing a complicated scene I'll sometimes draw the individual parts separately and put them back together in Photoshop. In this case, most of the figures were drawn using Layout Paper--more opaque than pure Tracing Paper, but still translucent enough to see through. In this way, I basically worked in real media as I might digitally anyway, with each piece on its own layer.
Final Encounter (R, detail): I didn't need to draw the dragon bigger than this to get the detail I needed. However, to include the figures into a drawing this size, as they would be significantly smaller, would've meant they'd be drawn too small to detail them as needed. So, to include them all on one drawing, I would've had to scale the entire thing so the *smallest* figure was large as I needed. That would've made the whole thing much larger, unnecessarily so, probably close to 16x20" for an 18x24" painting. Because it happens that the smallest figure was a Halfling. I still don't have the painting back at the moment, but it'll be up at some point.
(L, detail) Droid Commander: There's no reason that I drew this on toned paper other than whim.
Battle Droid: The final illustration here featured a "line-up" of various droids. Since I wanted a little flexibility to swap positions or flip them (particularly if the Art Director asked), I drew each of these separately, and then put them together digitally. So each droid is its own drawing, but two of them were expanded universe droids most of you don't know, and the other was drawn on darker paper and didn't read that well as a drawing (once put together digitally, it didn't matter).
Anne Bonny (alternate): When illustrating "Heart of a Pirate," my initial sketches had Anne much more boyish, as described in the story. After all, early on Anne needed to fit in with the men. I tried to keep her a bit feminized yet, even with her breasts bound and baggy clothes. The author had some different ideas for her portrayal, so we hashed it out and I re-drew her according to the specifications.
Balance 2: I've said plenty about this painting, but only showed this one with greyscale over it. This was the initial drawing.