How cute. Half- moon is my favorite! Sometimes I have trouble with balance poses. I found Leeann Carey has a free yoga video that talks about a Sitting Bone/Heel Connection in standing poses that is really helpful. Thought your readers would like it: http://planetyoga.com/yoga-blogs/index.php/free-yoga-video-kps-sitting-boneheel-connection/
I find if I keep my muscles tight (except the jaw) and if I concentrate on a fixed point the balance is much easier. Try it and let me know.