I always find it a shame when skies are blown out white in such a lovely photo. Seeing just a hint of blue though I was optomistic!
-use magic wand tool to highlight the sky
-play with tone, brightness, hue, saturation and contrast to bring back the sky.
-I did not fuss over the interface between the vegetation and the sky which needs some work, but this is hard to do on a reduced quality photo as required on TE, but just to give you an idea of what is possible.