I do like the vibrant and colorful color palette you have, but the first and fourth photos are horizontal compositions for no apparent reason. In the top photo, the extremely out of focus tree does not advance the composition much to my eye, and the fourth shot, the one of the same little blond boy appears to have some serious, heavy background cloning that stands out. Same with the little girl on the tricycle-the cloning is obvious even at web size.
Photo #4 really is not a good horizontal composition; his head is too close to the top of the frame,and the entire left hand side of the frame shows us nothing but your copyright stamp. I think cropping off the feet of both children on the brother/sister portrait,as well as the girl's foot in the first tricycle shot is something you ought to try not to allow to happen.
Frames five and six are good examples of pictures that make absolute sense as vertical shots; frame 4 would have made a good vertical as well, but it makes a poor horizontal pose. I like frames 2, 6, and 7 quite a bit,and think those are the most refined poses you showed. I think had frame 1 been framed as a vertical, it would have paired very well with frame 6. I would rather see more of the child's body than the tree in frame 1; 6 corrects that by emphasizing the child,and minimizing the out of focus tree bark that dominates most of frame #1's entire left hand side.
I hope this C&C doesn't come off as too harsh, but that's the way I was taught to pose and frame; horizontal portraits minimize the size of the sitter's features, and almost invariably a horizontal shot becomes an "environmental" portrait since it shows so many degrees of view. In frames 2 and 7 and 10, there's an actual "need" to orient the camera horizontally, and those poses all make sense and are sound poses. Frames 1 and 4 are shown as horizontals, but the situations and the amount of the subject shown are poorly-suited to horizontal framing. I think if you can fully comprehend what I am trying to say here, you could elevate your posing and framing up several notches just by trying to look at some of the 'secrets' of people photography and eliminating what are called "incomplete poses" and "amputations".