Theres a fun little exercise you can do using film stills as reference. Super helpful for sharpening those landscape skills. Take some time to grab some stills you find interesting from a site like Evan E Richard's Blog set a timer for 2min, grab a big blocky brush in Photoshop and paint as much as you can before the timer goes off. Only focusing on big shapes, color, and composition. Repeat for an hour or so its surprising what you pick up.
Heres a few I did a couple years ago in school. Really need to do more