I usually try to find a detailed map of the area I want to draw on the Internet (the links section at
http://civ2.sidgames.com has some great map resource sites). I then draw a grid over it using PSP and then open the MapEditor to make a map of it. After that has been done I pick up my atlas, or perhaps some other digital maps to do the rivers, then the elevation bit (hills and mountains) and finish it with the rest of the terrains.
I usually use grassland to fill the map, since I draw my maps in a very orderly fashion I really don't have the problem of missing a grassland square.
Have a look at my map making guide (again at
http://civ2.sidgames.com) for some details.