Thanks for the advice. I'll try and get around to it if I have some free time, but right now I'm working on this week's challenge plus my life outside pixel art (yeah, what's that?) 

 Yeah, stay away from that copypasta. Any make the mountains more jagged and not that perfectly round snowcap. Use google images for photo references.

The trunks are fairly thick compared to the rest of the trees and I think they are just copypasted. You'll get more interesting picture if you create each tree from the scratch. I also find the black outlines on the mountains unnecessary. The snow on the ground doesn't have black lines so why use them elsewhere either?

Other than those the picture looks nice :)