Original imageThis image is the original I will use for color development in Photoshop.

Hue/Saturation The hue , saturation and lightness of an image can be altered independently using the Hue/Saturation palette, sadly a lot of quality is lost when this is changed however different measures can be taken to ensure a good quality image.
In this example I duplicated the original image layer and on this I used the Hue/Saturation palette to make the color change very drastic. I dragged the hue slider to the far left while dragging the saturation a little to the right to intensify the color. then, returning to the main window, I set the layer's blending mode to Color. This made the original image below's color the same as the duplicated layer, it retained quality whilst changing color.

ColorizingUsing the same Hue/Saturation palette an image can be colorized, this option can be chosen by ticking a small box located in the palette. It will alter the hue slider so that it goes from red on the far left all through the color spectrum to red again on the far right.
To achieve this particular image I opened the Hue/Saturation palette and changed to colorize, then i moved the hue slider to green and the saturation slightly to the left to reduce boldness of color.

Intensifing color in selected part of image
Parts of a photo can be independently modified using selection tools in Photoshop select them then different palettes to change each part respectively. I used in this image the Marquee tool with a feather of 30PX because only the color of the sky is to be intensified and since the majority of it is rectangular the tool is appropriate. The feather ensures for better blending of the image overall, also I changed the tool to 'Add to Selection' so that I could also select smaller parts in between trees and change that also.
After I had selected what I wanted I created a new layer via copy so that could change the sky without affecting the original layer. Next I opened the Hue/Saturation palette and dragged the saturation slider to the far right, intensifying the color greatly, however doing so made my image very grainy. To correct this I used the Gaussian blur filter to softer the top layer of sky, then I set the layers mode to color. This corrected any quality loss in the image.