I am by no means an expert, but here's my crack at them:
1) I like this shot quite a bit. I think it would be compositionally stronger if the fence was going into the frame instead of out of it. Maybe if you could've pulled back a little and turned right just a tad? Colors look pretty good and the slight tilt to the image helps it quite a bit. I think it would've been significantly less interesting had it been straight up and down.
2) Seems nice and sharp with a nice vivid green, but I would've liked to see the entire leaf, and I find the shadow on the camera left side of the leaf kind of annoying and distracting.
3) Very nice, could've used a slightly bigger DOF (smaller aperture) to bring the underside of his chin into focus. Also I think it would like to see it somewhat brighter. The eyes are tack sharp which is critical when photographing anything with eyes. Also, if he had been looking into the frame instead of out, it would've helped.
4) Doesn't interest me very much, but that's just my personal preference. I think this shot is hurt by the fact that there isn't one clear subject, all the flowers have equal dominance and presence in the shot, and the one thing that would've helped the shot a lot (the bee) is severely out of focus.
5) Nice and sharp on the eyes again as well, but you cut the dogs head off, and compositionally it just looks like a snapshot to me.
Overall, very nice work, especially for a beginner. I look forward to seeing more. What lens do you have with your D60?