Might I ask how did you make the grid, the latitudes and longitudes? I use Inkscape, but I'm not terribly good at making things there equidistant and the like. I find it much more easy in Photoshop (ironically, since vector programs should be the ones where you can draw technical diagrams and blueprints), but I'm sure there's something I'm missing. Also, what do you use as reference for the grid?
It's what I've been doing. I've been searching some kind of grid generator, but no luck yet. My strongest problem is usually finding appropriate "gridded" maps for the region I want to map. Hard to do when you want to make a map of Mars, but anyway.