Despite having tried learning a good dozen or so mapmaking and drawing programs, from Gimp to AutoCAD to Hexmapper and AutoRealm, I still mostly make my maps by hand. When I'm lazy, I might search the net for few ready-made ones, or buy pre-made adventures.

In the past, I used a style similar to old D&D hexmaps, or the generic "fantasy map look" that is well-presented in this thread. Lately, I've started using real world geographical and orienteering maps as a baseline. I find this modern style more informative and easier to draw than elaborate symbols. I also use ASCII-style numerical and alphabetic notations on grid paper.

If I ever get a CAD program with good key shortcuts, I will start drawing my dungeons according to real world technical standards. Because I can.

My hints for mapmaking:

  1. If you ever find a program with good key commands, forget the mouse ever existed. Instead of drawing, learn to use XY coordinates and make those objects go exactly where you want them to!
  2. Forget looking good. A map is for telling where stuff is, being a work of art comes strictly second. Emphasize only key items that map is for such as nation borders, roads and rivers, and leave all needless detail OUT!
  3. A table or two for random item generation accompanied by a few rules of thumb for how they affect their surroundings (f.ex., rivers flow downhill, mountains gather moisture and stop clouds etc.) will help you seed your world with intereting stuff.