I like the use of slate rock in the sketch. Others would've chosen to go with more traditional and easier drawings of rock. As for the use of your own character, very well done. You're making the artwork yours. You don't want to carbon copy anyone else's work. I've seen many times where people will copy others' work. Emulation is very flattering. However, that only gets you so far. I would like to see the finished product. I'm looking forward to it! As for going out of your comfort zone, keep on! Push yourself to newer heights. You'll be surprised by the results!
You can barely tell that a Photoshop filter was used so that's a BIG thumbs up. The uniformity of the shading is also very nice. The lines are subtle yet, hard giving the rough feelings of rocks. I'd love to see this with a vast rocky background but, even without it you still get the sense of a wide open space. Just by studying this picture you can sense power, stillness and bit of concentration. For being rushed it looks very good. As a matter of fact you can actually see the rushed sketchiness in the shading and it makes the picture look more original. Great job overall!
It looks like your character is a god of a new world and look to the horizon and say "That's all my world. I will change everything. Oh humans a new era has begun." Sorry I have too much imagination. xD