So, in my mind, I deconstruct the map that I wish to make into sets of items or layers... maybe, if I show you it would make more sense. Here is a map that I made for a game that I hope to run someday soon.
1. Base layer - draw a rectangle, mix some blue, and fill in the rectangle.
2.Ground layer - I use the pencil tool to free hand the outline of the ground. In this case I mixed a darker brown for the earth and chose a tan/sand color for the shoreline.
3. Trees layer - Next I draw a small sample of circles, fill them in with some green color from the mixer, and then cut and paste my circles until I have enough to make a forest.
4. Rapids layer - I needed to show rapids in the river so I drew the needed shapes, colored them a lighter blue, and then close a pattern for the rapids and whirlpools to differentiate them.
6. Rocks and Movement Info layer - I drew a few rocks and placed them over the rapids area. I added text boxes to give movement information for players to use if I ever get to run this game.
7. Event markers, Title box, and border layer - Lastly, I added "event markers" and a title to my map. Most importantly, I added a thick edge border to cover up all of my imperfect drawing of shapes on the lower layers...
It really sounds more complicated than it is. Map making is only as complicated as you wish to make it. As long as the map conveys a good idea of the terrain and helps a reader understand the action being described then it is a good map. I hope that this helps a little for those who wish to make maps to describe a wargame battle.