I can't believe no one has mentioned the evil on-camera flash! These pictures all look very over-exposed and have a very flat on-camera lighting look to them. things that would have helped: off camera lighting, reflectors for fill from one side of the other, shooting at a different time of day, shooting at a different angle relative to the sun, shooting in the shade, using ambient light only, not using on camera flash, watching you histogram to make sure you're not clipping highlights, and so on.
I like the poses and the expressions, and the scenes, but the exposures need some help.