Well, the way you drew the characters seems pretty good. Here are some things I want you to change though
Make the left girl's like this i.imgur.com/nz48BUD.jpg
Make the right girl's face serious, not sure if I have a reference that's good enough. But um.. try to make her face serious, and also she should be looking down, not up, since she's kneeling.
Which brings us to our next point, she should be kneeling before her, not sitting next to. The view should be from the side not up front, and there should be a bit more space between them. If there's something you didn't understand, feel free to ask! I would gladly help my favourite artist. Hope I am not being too much trouble.