On #1 with that much light, ISO 800 is completely unnecessary. You can back it down to 200 and still shoot at 1/250. A good choice of subject with the backlit because its translucent enough that it makes the whole body 'glow'. Definitely shot at the wrong time of the day without somehow softening the light and the cropping leaves a lot to be desired as has been mentioned.
On #2 you've got a good idea in that you have a subject that has a background that gives context. The rest of it doesn't really work. This is not an image that benefits from a centered composition and inclusion of the house is not helping it at all. A good idea to ask yourself when composing is not what to add to the composition, but what I can I add by removing elements. Also, your subject is in harsh shadow for a good chunk of it and the shadows are not attractive. They conceal subject elements rather than define them.
#3 is underexposed, white balance is off, the direction of the light shadows his eyes (this can sometimes be dealt with in post, but not always). The vertical element of the composition are good but the horizontal in the case should be centered or at least enough to bring the subject's ear into frame.