Newbie Soccer shots

Hi,
I started shooting with my first DSLR over the summer. My main topic is my daughter's soccer team. Here are three shots that I got during the fall season. As I am new to just about everything, shooting, post processing, posting etc. I would like to get some feedback. Thanks.

1:

Something that really sticks out for me here is your background. In the first two shots, the grass and sky are competing and split the image in half. In the third, the background is entirely grass and the image has that "normal" perspective. Try shooting lower to the ground while kneeling or even laying on your stomach.

Otherwise, the shots are technically good. The only other thing that I would care to mention is the crop/composition in the third shot. I'm not a big fan of cut-off limbs unless you are going for a very tight shot. This shot isn't quite tight enough for me to let the crop pass. I suggest either a tighter crop emphasizing the faces or pulling the crop out (if you had cropped it already) to focus on the action.