Currently my method is just making a general mountain shape with the terrain tools, then placing rocks on it and trying to paint on cliff textures to it.
Thanks for the advice, i'm going to do a bit of reading up on it later today.
The way I most often see things like this done, both digital and physical models/sets, is that you lay down your base general shape, and then you add/remove materials to give you the fine details, usually working either from the top of the model down, or the base and going up.
What methods are you currently using to generate it? Sculpting convincing and interesting looking mountains is a really hard job, so don't beat yourself up too much if a lot of your early attempts aren't working out the way you want.
Spend lots of time on google images looking at various mountains and rock formations as well. Some time reading about geology and how rock formations are create in the real world can also help a lot as you will have a better understanding of what exactly is going on and how things should look.