I encourage you to sell sketches ;O They're pretty freaking awesome. And they sell pretty well, last I saw o3o'
A little tidbit from my brain- I think you would also be good at Dog anatomy. If you would like, I'd suggest starting out with a Lab or something very general, being closer to the shape of a T-rex head (I think xD).
You have a very nice ballpoint/graphite style, and I'm sure people would love to snitch some of their own. ;3