I know I'm new but I have discovered something about this hobby. You can become creative without even knowing you had it in you. I'm gonna post a few pix about what I did on my mountain.
I created it with W/S foam and plaster cloth. Then I used their rocks molds and made rocks. I waited till they were dry and then glued them to the mountain using Weldbond, awesome stuff. I had to remove one from the mountain because it looked out of place and it pulled up some plaster from the cloth so it holds really well. Also, DAP patching plaster, great stuff, I used some to glue on some rocks and it works great!
So here's what I did. The rocks that I glued to the mountain have some gaps around them. So I used the patching plaster, two small artist's trowels, and water and a paintbrush.
Here's a blurry photo of a rock that needs the gap filled.
Here I used the small trowel to fill in the gap with the plaster.
Then the paintbrush to smooth it all out and water it down so it doesn't fill the details of the rock.
Hope this can help someone, I know there's many ways but I just wanted to give back because so many have helped me.