Haven't posted here in a couple of years. Have been trying to keep mapping, but life keeps getting in the way. Have some time and had a project I wanted to be working on, so here goes. Am doing this in Photoshop, 72 dpi, 2000x2000 pixels.
Basically a large island, with a medieval-ish culture. Low fantasy, so not much magic and whatnot. This isn't so much a new setting, as it is an update of an old one I really enjoyed.
So I start with what I call the "Ascension method" for landmass creation - though I don't know if he came up with it, or I just learned it from his tutorials. Black & white, Render -> Clouds; new layer overtop, fill 50% gray, set blend mode to "hard mix." Grab a round brush, I usually use 100 - 200 pixels and then go smaller if I need details, drop the flow down to 5-10%, and then paint in the cloud layer to create the landmass. I merge the two layers (though I keep a locked copy of the clouds layer, in case I need to adjust later) to form the base outline of my landmass.
I want my landmass to be floating, so I can easily select its shape so I Select -> Color Range -> Fuzziness 200, with black as the selected color, then delete. I want a mountain range more or less cutting the large island in half. I up the flow on my brush back to 100%, pick a color that'll contrast (I went with bright cyan), create a new layer and then fill in the area I want it to cover. Then I Ctrl-select the landmass, inverse and delete on the mountains layer to clip anywhere I went over the lines.
Now I switch to using the awesome Calligraphic Cartography brushes I found here. I got them here on CG, but there's no name on the file and I can't find the post I got'em from (I've spent 10 minutes looking). The pack is a zip file, containing three separate brush files: "Calligraphic Cartography Land Features," "Calligraphic Cartography Norse Buildings," and "Calligraphic Cartography Trees." If anyone can post me the url, I really want to give credit where it's due.
Okay, so I proceed to fill in my cyan area with mountains and rocky hills from the brush pack above. I mostly use mountains, but I want there to be a pass running through the range with a gap large enough for a large town/small city. I use the rocky hills brushes to border the cleared area. This part is important (for my method at least, I'm betting one of you veterans can tell me an easier method to do this): I put every brush on its own layer. Partially so I can shift them around later, but mostly because they're going to overlap and look...not great. Keeping each one separated will let me erase the overlapping parts without accidentally slipping and destroyed other brush imprints, etc. Time consuming, yes, but I want it to look good.
So, there's what I have so far. Next, am going to touch up my mountains and do the erasing. Then on to rivers, I'm guessing. And yeah, seriously, if you recognize that brush set, please tell me.