Your concept of uh, if I have the right word, volumes, there, looks lovely. It looks like the beginnings of a great tree - or the endings of one for a appropriate style. Taking it to the next step - defining leaves more or whatnot, if you do - was for me the hardest part. Best of luck with this - I'm really looking forward to how it turns out. Colours look great.
I'm hoping to do a lot of practice on trees and update my original thread these next couple of weeks - up in the country, lots of sketching study to do. Just have to recover from the driving test today and keep the birds happy.
