I think - if you want some composition crits - cut the edges kinda close to them you'd give them a "bigger" look as you also can increase the size of the pic showing more detail. The mini version shown here is not very true to all the work you've put onto it. It's fine to put the light behind the characters as it will slightly take the focus off the "border decorations" and aim slightly more towards the character's themselves.
Also, I think slightly more prominent shadows under then will make it slightly more, I dunno but better

Use the method like so:
http://fc09.deviantart.net/fs51/f/20...ZicToXemia.jpg
ignore the horrible colour composition and motive and just look at the shadow. i used a medium opacity and a fairly big brush for that one. Using a grey hue would probably distinguish their shadows more from the shadow of the snow.
It's only my opinion. Though :P You use it if you want.