C&C per req:
1. A nice image, and good composition, but the perspective is a little skewed. It needs a straightening and perspective tweak. As well, you've go some flare in the upper area and a blown sky. I would suggest doing a reshoot with the sun behind you. This will eliminate the flare and hopefully produce a nicer sky. Overall the image is a little too mid-range for my taste, that is, lots of grey, and little black and white.
2. A strong image, but it needs a diffused fill-flash placed probably about where the RH table leg is, aimed up to provide a little more illumination on your face. This one again needs straightening, and would benefit from your being not quite so close to the edge.
3. An interesting capture; I don't really have much comment to offer other than I think it would be better not to have cropped off the toes and posterior or the LH subject.
4. Not bad at all. A reflector to add just a little fill light to the LH side of your face, and perhaps a diffuser to reduce the highlights on your right forearm and forehead, but other than that, I think this is a nicely executed self-portrait.