Thank you very much for the tutorial!

I do, however, have some questions, if you don't mind helping out a photoshop newb

Q) I'm afraid I don't understand step 4 at all. Are you talking about the bush mode being in Overlay, or adding a Overlay Texture layer style?

Q) In step 6 you say to use a brush size of 1 pixel. I can barely get any paint on the canvas (so to speak) with this setting. What am I not understanding here?

Q) I presume that you do the painting with the Pattern Stamp Tool and not the Brush, yes?

All my mountains seem to glom together into one big range, not a variety of circular rises, as yours seem to do. It's a very nice style, here's hoping I can figure it out