Like the site, need advice

[spudspotato]

Hey everybody,
I've been worldbuilding for years now, but recently I have decided to put more serious thought into my worldbuilding and roleplaying. Of course, this is includes making maps for the worlds I design. The problem is, I'm not a very good artist and am pretty inexperienced using image editing software. I'm not gonna let this stop me from making a map, so I set about creating a basic landmass using gimp. I decided to base it on a real-world landmass (I have no idea if that's some shameful act here, but we've all seen an outline of Westeros rotated and put over Europe), and after some time I have a very basic, 2-color map, not showing anything more than the land, rivers, and sea. My main problem now is that I have no idea how to draw a mountain or tree symbol, much less duplicate a lot of them without looking cheesy or putting variation in my city symbols like some of the amazing maps I've seen here. I'm not looking to make something too detailed, I was amazed by some of the maps I saw here. Anyway, if anyone has some advice I'd love it. I have accesss to GIMP and CC3.
There's not much more for my introduction, but I'd like to say again that all of the maps I've seen here are amazing and well beyond anything I ever expect to do. Also, I'm glad there's other ASOIAF fans out there.
Trent
"spudspotato"

(I'm aiming for a final product that looks like one of the simpler CC demos or the old 1st or 2nd edition Forgotten Realms large map, but I have no idea how hard that will be.
EDIT: This is the thing I'm talking about.)