New mapmaker with a conundrum...

[Preypacer]

I'd suggest using the first few steps from Tear's tutorial, which is excellent for just what you describe. What is does is basically turning your brush into an "auto-coastline-making-tool". From there, it's up to you to pick style.

I did find that tutorial and it looks awesome. Trouble is, I don't have Photoshop and am working at learning GIMP. I'm at the first steps where you create the new layers and am already stuck since there doesn't seem to be an equivalent to adjustment layers in GIMP, so I can't get the Threshold layer in there, which seems to be a pretty critical step in getting the initial landmass shaped out.

Sooo... Yeah, gonna have to figure out another approach. Def. a great looking tutorial, though. I like the end results.

Edit: Actually I found what looks like a good Tutorial here ... so that looks like a good place to start.