This is both my first foray into cartography and my first post on this forum, so please let me know if I've done anything silly.

I'm making a world for an RPG campaign, and I'm determined to do it as realistically as possible. I started with tectonics to create landmasses and mountains, then created a basic elevation map, used Geoff's Climate Cookbook to determine climate/biome groups, and combined elevation and projected relative rainfall to create rudimentary water features. I even used G Projector to convert my world map to a Robinson projection, since I'll need to have at least a bit of realistic proportions to determine travel times for my players.

You can see everything I've made here.

However, none of it looks good enough for me to feel good showing it to my players: not the caliber I see here on Cartographer's Guild. I would love to make a map with a classic fantasy feel, with the illusion of parchment and ink. I have almost no idea where to start. I've followed a few online tutorials, but I abandoned a lot of them halfway through because either they required more skill than I possess or didn't seem to be creating the feel that I'm looking for. Part of it is that I'm using GIMP, and I've never used a program like it before (not even Photoshop).

(On a slightly-related note, I tried following this tutorial for making parchment in GIMP, but GIMP keeps crashing when I try to add the bump map. Not sure what's up with that.)

I suppose what I'm asking for is any general advice for creating classical fantasy maps, or any specific resources for GIMP. If the best advice there is is just "get good," that's okay. I can keep trying.

Thank you very much for your time!