Woodland scenes are beautiful (just take a walk in one or search for woodlands in google images if you can't. But there is so much going on! There are trees everywhere, leaves everywhere, and the wood just seems to go on forever. How do you capture all of that in a painting?
The answer, as ever, is to simplify. Squint your eyes and all the detail will disappear, just leaving you with the large masses of tonal shapes. These give you the 'skeleton' or framework for your painting. Once you have seen the few basic tonal shapes that make up the scene you can plan them out on your paper. And once again, when you come to paint, don't get bemused by all the details. Paint big simple shapes and slowly add more detail if, and only if, you need to.
This woodland scene I painted today was from a photo, but I altered and amended and simplified it right down to the basics. But I think it works. Why don't you have a go? (There will be a video of me painting this picture on my new watercolour landscape course in a couple of months time.)