I like 2. 3 would have been better without the branches and a couple of steps left so the tree is not in the background? Not sure what was to the right. 4, maybe a little off the top to eliminate the trees. Nice shots.
#1 needs to be cropped to a vertical portrait. Exposure is a little washed out in her face and arms. That could take a little tweaking.
#2 exposure is better but I like her expression better in #1
#3 good action shot
#4 is out of focus, not much you can do to improve that. Anything with dandelions has to be tack sharp.
The girl is poorly separated from the backgrounds, light wise. Direct sunlight sucks, even if there is some overcast to soften it some. The light is usually way to high and causes the raccoon eyes (dark eye sockets) or is to low and causes squinting.
People are tall and narrow and their faces are higher than they are wide, making a horizontal (landscape) frame less appropriate than a vertical (portrait) frame. Many on Facebook are just copying each other's mistakes.
I used to get an obscene amount of money to take photographs of people outside on location in the daytime. It was only rarely that I did not use strobed light. Maybe because I am a control freak, but one of my main photographic precepts is "Take control of the light".
I used open shade when it was available, and made my own open shade when it wasn't.
Shoulders square to the camera is called the 'football players' pose. It isn't very dynamic, and it's not all that flattering to most people. Angle the shoulders, but be sure both shoulders are in the shot.
They all seem a little underexposed except for the first one? The lighting is also pretty flat, but even so, there are small shadows in areas where you don't want shadow, like in the eye sockets and directly under the nose.