Actually, instead of using brushes, you could create a base document on which you draw all your mountains one next to the other. On the layer below, you paint the inside of the mountains with white, and then you merge the two layers together. That way you won't see the hidden details of the first mountain when you put a second mountain over it top. Afterwards, when your entire mountain range is done, you can just "colour to alpha" the white out of the layer and what you're left with is a nice black outline without any overlap issues.
Great job with those colors; subtle but effective. One nitpick: I think it's a 'strait' if it's a body of water, 'straight' if it's a line.
"I like a look of agony, because I know it's true."
Yeah, I would agree those colors fit quite well.
Consider making the text a less-bright white
(or semi-transparent (barely)) to eliminate any
Your mountains are great. I look forward
to following this project
The best maps are the ones we like the most after looking at the longest.
When I'm setting up the full size map, I've read it has to be 300DPI for printing but Photoshop settings is PPI, how do you allow for this? Also should it be CMYK 8bit too, just in case I want it printed in the future? When I did the one above I used RGB.
@Caenwyr: Great advice, thanks that will solve many problems!
All the advices regarding print are correct here, I'll just add that it's best to finish your work in RGB and then convert it to cmyk. With RGB you'll be able to use more filters etc. Just keep in mind that when converting to cmyk your colors might change a bit. I usually do the conversion in Photoshop via edit -> convert to profile, and select general cmyk profile, unless I know what color profile the printer is going to use. Also, converting to cmyk via convert to profile will flatten your layers, so save it in a different psd file first. 300 pixels per inch is good.