Forest references, colours and sketches

So above is a quick little painting I did about a year ago and I've been asked to do another painting based off it. I'll admit I'm kinda nervous, I always find it really nerve wreaking to do commissions but at least this one's fairly cheap and she doesn't have to take it if she doesn't want it.

I ended up looking up some references and doing some composition and colour tests. For composition I went with the top right one, it took a while to work out exactly what I wanted though I had the base idea pretty quickly.
For the colours It was mostly trying to find the right blue that merged with the red, green and purple into something I liked. The colours I ended up picking are: Phthalo Blue, Permanent Mauve, Magenta, Perylene Red, Quinacridone Sienna, Winsor Yellow and Winsor Green.

I've stretched the paper and started sketching, just placeholder trees for now, I'll need to turn them into something a bit more realistic tomorrow.

These are my main references, the ones on the left for composition and on the right mostly for lighting.  (click on them to make them bigger.)
Top left was found here.
Top right is 'Call of wandering' by Janek Sedlar, found here. 
Bottom left was found here. (wallpaper site. :/ )
Bottom right is 'Behind my house...' by Kilian Schönberger found here.