I make all my maps through gimp if I don't acquire them off of google and even then I still tweak them through gimp. What type of maps are you wanting to do. Overland, Towns, Dungeons, Battlemaps? There are slightly different procedures in doing them but they all boil down to the basics of finding your background texture ( choosing a simple color works also) if you want one, finding tiles to work with, and piecing it together. It's taken me years but I gathered a collection of tiles that I use and I'm still collecting them. I'm close to 8 to 10 gigs right now.