1st photo: weird expressions, and probably wrong side from where you're taking the photo. go to the other side where you can get the most eye-contacts or at least they seems to be looking at you. you'll see the big difference.
2nd photo: focus is slightly off and try to include the whole body, esp her feet.
3rd photo: nothing in focus, no main subject and wrong angle too. capture them running towards you and so it means you have to be ahead of them! choose a person to focus. but they will be running towards you and that means you have to be fast.