Well, the thing is that they all look the same...some bigger some smaller but all carbon copies (or very close to being that way). Try varying what they look like, give them some different shapes for the peaks and ridges. Also, add some rounded foothills. Lastly, and this is my opinion that no one ever listens to, you might want to make them the same brown as on the coastline since you are using that as an outline (ie hand drawn with pen and ink) color. Take a look in the Mapping Elements section for a thread by Wag on mountains.