Basically, this idea came in mind when I was mapping. Strange huh? But, basically I start off and other community members may post another section of the tutorial. So its like a.. Build by post tutorial. It can be anything you make it, Battlemap, Indoor map, Overland map, City map, Etc..
Eg: Step 1 make a document of ### x ###.
Step 2 (another forum member) Set to default colors (black and white.) Filter > Clouds twice and filter > Difference clouds.
Step 3 Etc.. Etc..


Ill start it out.
File > New
Resolution > 300
Width #### Height #### (Remember that the scale your using should be taken into account. Eg: 1 pixel = 1 mile or 1 pixel = 1 KM. And so on and so forth.)