I'd suggest checking the daily critique on http://www.radiantvista.com/news/
- after you've seen a number of them you'll be better able to critique your own shots.
I'd start by just identifying all the major elements in the shot and asking youself did you intend to include or not - eg: in the first shot, the background sliver of shore, or the branches in the top left. Also when taking the shot run your eye around the frame for intruding elements - eg: the blades of grsss poking into the frame on the lower right (knowing and using the tools of post processing is important).
I like the second shot (you could clone out the intrusion in the bottom left) - I like the framing of the foreground trees and the vertical patterns of the grass.
I also like the third, - compelling in an abstract, Halloweenish kind of way. Are ther power line running throught the bottom third? Again that's a bit of a distraction.
The trick is to deliberately include and exclude elements either by changing position, framing, or focal length, and PS as a last resort. In a perfect world, everyting in the frame is there because you explicitly wanted it there.