I like the way you did this. You can add color to this kind of thing really easily with shading filters. Not saying you should, but I just wanted to comment on the nice technique. :)
The only thing I don't love is the edges. Do you use a lot of smudging? It might speed up your process if you could find a way to work with the smudging in a more "solid". Like, I've found it helps a lot if you try to work in a way where, at any step of the process, you could stop and it would be "finished". It might take more time trying to work like that in the short term, but it really speeds things up as you move along. I'm sure you're already doing this sort of thing, but I just thought I'd mention it, lol...