Hello! I'm still a bit green with regards to both digital cartography and this site I'm working towards a "world map". I've been RPGing since about 1981 and have done a few simple things in digital, but I'm really looking to move ahead. I've got a world design in low-res at the moment and was wondering if I could get some thoughts on my next step. (I'm using GIMP)

My goal is to have a generalized world map, then produce kingdom/region maps and finally area/adventure maps. The map I have at the moment appears to be at
72dpi (I didn't choose this, it came as a result the software I used to layout the continental shapes) ....I'm going to need the map to be available for larger print.
What type of resolution should I be going for and is there and easy way I can (using GIMP) achieve this off of my present images? (my land is isolated at the moment, with everything else being transparent)

I've gone through several tutorials here and have has some good results, I've just not worked on something this large. (or was supposed to "represent" something large) I just want to make sure I don't do something that I'll regret at later stages.

Any info will be most appreciated