I have two different maps I am going to work on. One an island 40 miles long, and another dungeon which will be fairly large. I am having a hard time deciding on how to determine the scale of the maps. I have seen plenty of dungeon map tutorials on here and that looks pretty straightforward but the island has me somewhat puzzled.

Should I base the size of my map a certain resolution and scale based on the size of the object I am going to map (the island) or should I just pop up a new image 2000 x 2000 pixels @ 72ppi and start drawing? I see lots of getting started tutorials out there dealing with the act of drawing, but I think I may have missed the ones that deal with scale and image resolution. Or is my Drafting and Design background making me too nitpicky? Heheh.

Any help would be greatly appreciated. Thank you in advance. :-)