Yeah, those mountain ranges are not great.

The first thing I would suggest doing is that you need to overlap your brushes. At the moment, other than a few small areas they are all just brushes independent of each other and so will never look good. To solve this you need to join them up. There are a few ways to accomplish this and still make it look good. Firstly, you can do a search for the clone stamp teqchnique which allows you to place one vrush over another without the bottom one showing through. Another technique is to place your mountains on two or three different layers making sure that any brush that overlaps another is on a different layer. You can then easily erase the part of the mountain that is overlapped.
Another thing you can do is to link them with colour. For instance, those mountains are very dark and in between them all is your tan texture. If you were to take a similar dark colour and paint between the mountains to connect them , removing the tan space between them then they will look better. But this would then need smudging and blending in to your paper texture to look any good. And also your mountains are placed so regular that this still probably wouldn't look great.

Another thing I would suggest doing is not making your ranges so straight. Suggest spurs etc. by just placing one or two mountains as an offshoot from the main range.