Honestly, regarding both scenery and track route. Try to just imitate what you see in other tracks. It might not always feel like entirely your creation but I think you will get a feel for building nice sections that way and soon you will find your own style with both route and scenery.
For example try combining sections from different tracks into one, perhaps looking to see if you can improve the sections in some way? Make it smoother, easier etc.. Should be a good excercise for building
I started out basically trying to replicate tmjonas snow style even though I was nowhere near his building skills, but what came out helped me to become a better builder and to find my own style!