Hi,
today I had a friend look at my handstand, and he said that my elbows are overstretched (not sure, if this is the correct word; bent in the "wrong" direction), so that my arms look a bit like an X with the elbows being nearer together than the hands or the shoulders. I also see this problem at other people's handstands sometimes, but never know what to tell them how they can correct it (just "straighten your elbow" doesn't seem to do the trick for most people).
After I was told about my elbows, I could correct a bit it by concentrating on lengthening my whole body, trying to get my toes as high as possible (and especially getting the shoulders as far away from the hands as possible).
Do you have any advice, what to do about it?
P.S.: This showed me again, how important it is to have someone giving feedback in handbalancing 
He didn't ever have that problem himself, so he didn't have advice how to correct it, but knowing about it is the first step to correct it imho.