Thank you for the redlining, I can see what I should work on!
Textures are pretty important for the background, so I make sure I have a variety of brushes for what background I'm going to do (I have brushes for the grass, foliage brushes, and my pen brush for smaller details), and if I don't have a brush made specifically for an object (like the tree bark) I tend to use multiple textured brushes together and experiment!
As for backgrounds I use separate layers for each part of the land and start with base colors with low saturation (The log, the trees, the grass, the bushes, and the tree leaves each have their own layer) They'll look like blobs or flat shapes at first, but then comes the textures and details
I use various brushes to create the textures for each object in separate layers, then I lower the opacity a bit. After that, I use many more layers to create the shading and lighting (with slightly more saturated colors) separately with more texture brushes!
If you want the shorter version: Start with shapes, then build step by step on the details. Different brushes can be very helpful with these details, and last but not least, practice
Winter Month: 1 
Day 
Fog
