My Sketchbook

[Teriopi]

Hello all! After a long time spent lurking, I decided to make my very own sketchbook thread....altho it seems to have gotten lost before it found it's way to the board, so I am trying again!
CA seems like a great place to get honest feedback on one's art, and it's something I can never get enough of.
A little about myself: I graduated with an AAA in Fine Arts from a community college. I've tried my hand at all kinds of media, but seem to have settled on digital this last year or so. I do most of my work in Photoshop, with the odd sketch still being done on paper. I'm big on medieval fantasy and have only recently begun pushing myself towards sci-fi and tech subjects.

[Teriopi]

Here's two small sketches done for my next couple of paintings. The first is a large cavern with waterfalls flowing into it and small communities that have taken up residence. T'other is an outdoorsy area with bridges spanning some of the rivers.
At this stage, any words of advice on composition, or anything else that needs fixing, would be super. Thanks!