Seriously though, it depends what area you want to make blank maps of and how accurate you want the map to be.
True. There are great maps online that simply aren't editable. My own interest is Scotland of course and I used David Boothroyds maps. However a few months ago I decided to make my own from scratch
Essentially it's the same principle. I like white on black as it shows up colours better.
Other than that use Paint and have a steady hand