You can find videos that take you through post-processing with techniques that are applied to the whole image at YouTube. If you follow the instructions, several methods are given to prevent typical problems with post-processing, most notably over-exposing (also called over-saturation). Here is the website: http://www.youtube.com/channel/UCozGBv-6_cqi8T9hSAN236g

The channel is named "Photoshop for Science and Microscopy" and it features videos that I assembled.