Exposure, settings etc all seem fine to me. But first things to jump out is the composition. Some can fix with a crop, others are learning experiences. Remember, if it doesn't add anything to the photo, don't include it.
First one is easily cropped. The background doesn't really add anything or set a scene.
Next one... You cut them off at the waist. In general don't cut people off at joints, it looks better cutting through limbs/sections of the body. In this case coming down further and cutting the off along the top area of the thighs would be better, plus you would get all their of their hands in the shot.
Third. This is better and you can see the last point I just made in action here. Cutting through the thighs is better. But the top adds nothing.
Keep shooting. Looks like you got some great subjects to work with.
My last bit of advice.... Don't be afraid to fill the frame with your subject.