Okay here's what I've done so far with my new map creation:

I found a topographic map of mars. Coincidentally, the low areas were blue, the high mountainous areas were red, and the middle areas were greens and yellow. Perfect! That shows me, literally, what the land would look like with oceans and seas.

So I cut this one area that I like out, and pasted it in GIMP as the base layer. I put a layer over top of it and outlined the coastlines, rivers, and lakes.

Next I want to figure out something for the mountains. This isn't a mountain range like, say, the Rockies, a long thin band like we see on most maps. This is more like the Himalayas in China; one big blobby wart with a few blobby warts around it. So, I'll have to break my skull open and reach in with my fingers and poke around in my brain for some ideas.

So, now that I've outlined the coasts, all I have to do is outline the mountains and I can delete the base image of mars. Should I make mountains, coasts, and then the terrain features (forests, hlls, etc) each in their own layer? If so, what should be the opacity of each of these layers?

And could someone help me make mountains? I'll post what I have so far.

Thanks! I feel very good now.

EDIT: It's 10 MB and I can't figure out how to post it. lol