Coming from a guy who knows nothing about backgrounds, it looks like you did a pretty good job here. You could've put a hill or something in the far background to make it a bit more interesting, but it's not necessary. I'll say that the tree looks good, though.
Lyra looks great here! I particularly like how you interpreted the folds in the fabric of the hoodie--it really adds a touch of realism to it. The only improvements I can think of would be to beef up the shadows behind and below Lyra, and to perhaps rework Lyra's posture so that she's visibly putting her weight on the tree (I think it might seem a bit more natural, but that's just my opinion). Otherwise, this is an adorable piece! Keep up the good work!
Thanks I appreciate the feedback. The posture problem is actually because I started it off as a sketch of her standing up, and then later decided to tack on the background without adjusting the sketch. Heh, such a lazy mistake.
It's not really a "problem," so to speak... And not so much lazy as 'resourceful to a fault' perhaps. It actually looks like she's just leaning her head against the tree, which works here. I was just throwing it out as "hey, you could do this to kick it up a notch," I don't know.