The first thing I would ask, in offering advice is, "What is the scale of this map?" Details are somewhat ambiguous if the viewer doesn't have a frame of reference. If the mountain base is say, 10 miles at the widest point, that gives us a large of island of roughly 70 miles high and about 210 miles long (rough guesstimations)? Increasing the size by tenfold would allow you to view the map in very fine detail, possibly including the actual layout of houses and farms and the like.
The second thing I'd ask is, "How much detail do you want to include?" If you're not interested in being able to zoom in to count the chickens in Miss Betty's barnyard, you probably don't need to zoom in quite that far or include that much detail. However, being able to zoom in that close would allow you to pull areas out of the map to lay out encounters or any number of historical applications, right down to the precise location of King Youknowthatoneguy's burial site.
Adding detail to a map like that can make for a lot of work, so you may wish to consider what you need and what you want in comparison to the scale of what you have.
It's a great looking map, by the by! Well done!