2 easy ways to improve your photography right now!!
Shoot in RAW format not JPEG
Buy Lightroom 5 (or other editing software)
JPEG files are ok for taking snaps, but don't like being manipulated as they are already compressed. So every time you edit/save a JPEG it will degrade in quality.
RAW files on the other hand contain all the information in the photo and can be processed repeatedly with no losses.
Here's a quick example editing your original pic in Lightroom (As its a JPEG the results aren't brilliant)
Original image
A bit of editing has darkened down the sky, brought up the shadows in the foreground etc to give a more balanced pic.
If this was a RAW file it could be done with no loss in quality and the results would be much better