In your first link, anytime you shoot into the sun, you will get some spill over into the rest of your subject usually resulting in low mid-tone contrast. The framing seems a bit akward for me...parts of the branches are cut off and parts of the sun are cut off. The branch at the bottom left is particularly bothersome and the branches at the top left form leading lines leading the eyes away from the photo. All in all, it's a picture of a tree without an interesting background. Sometimes a lone tree can make a very interesting subject...sometimes not.
For your second link, I have many of the same comments. The sky is much more interesting in this photo and it looks to be exposed well. Kudos for taking photos at a different angle and perspective. My main hang up on this one is the focus point seems akward and not really thought out. Looks like you used the center focus point and didn't use focus to emphasize any particular part of the subject...the middle of the post is probably not what I would have chosen, and probably not what you would have chosen if you had it to do over again. I would have either adjusted the focus so that either the very bottom of the post was in focus or the very top...I think the very top would have probably worked better, but either would be preferable to the middle of the post.
For the third link, it looks like the focus is a bit soft, but it could be a result of the very shallow depth of field...a smaller aperture would have probably been helpful for this shot. The other part is that people's eyes are naturally drawn to the brightest area of the photograph, which, in this case is an overexposed, busy, and out of focus background. It creates disunity and, again, just seems a bit akward.
On the plus side, it looks like you either, naturally or intentionally, used the rule of thirds for all of your images to help put your subject in a strong position in the frame. Now we just have to work on making sure the focus is on the area you really want to emphasize and work on getting interesting backgrounds that add to the photo instead of backgrounds that just happen to be there.