C&C per request:
Shot 1
- Lighting: Looking at the uncropped version I can see that you (or your camera) did a decent job of finding the middle ground between the bright background and your son. In the cropped version, however, you've left yourself only darker areas of the original (except for a slightly brighter spot at 3 o'clock in the cropped version), so the whole image comes off as underexposed. I think you can brighten up the entire crop to get his skin properly exposed and then burn the background where needed so it's not overly bright.
- Color balance: The color balance is a bit on the cool side. Again, this is not surprising since the remaining subject was originally in the shade of an image with both shady and sunny areas.
- Composition: I actually like the composition. The most interesting portion (the fingers with the dirt sticking out between them) is approximately at a rule-of-thirds point, you've avoided cutting him off at the elbows, and his left (near) arm follows a nice diagonal from lower right to upper left. The only nit pick I have is that this particular angle to the arms, combined with the intertwined fingers, is too reminiscent of praying hands for me (which just doesn't really jive with the dirt).
Shot 2
- Lighting: I think it could use a touch more brightness, but this might be better accomplished by dodging the sole of his left (top) foot rather than universally brightening the image too much. The reflector could use being just a smidge brighter (IMO), as it's coming across a bit gray, but at the same time his right sole and left shin are bright enough that you don't want to over brighten them.
- Color balance: I think the color balance here is pretty good, and I would see how the shot looks after dealing with the brightness before worrying about the overall color balance.
- Composition: Thank you for posting the recrop - that was my first reaction upon seeing the originally posted version of this shot. I like the tighter crop; the extra reflector was doing nothing to add to the image (if anything the wrinkles were detracting from it). The tighter crop works much better. It is pretty well centered horizontally, but because you can see the legs heading out of frame to the left and top the image still has some dynamic feeling to it (unlike a centered image which doesn't break the frame).