This response is based on the assumption you are using Photoshop CS2 or CS3 for your image adjustments...
if you are shooting digital images, I'd recommend shooting in RAW format (if you aren't already). When you first open RAW images in Photoshop, you are presented with a very comprehensive adjustment window that allows you to make non-destructive modifications to the image (color temperature, contrast, black level, vibrance, brightness, etc.).
further, in Photoshop, you can apply Adjustment Layers that can be deleted without hurting the underlying image. Adjustment Layers affect the appearance of every layer underneath, but do so in a non-destructive manner.
Whenever possible, make image touchups on separate layers so they can be turned off/deleted if you change your mind.
If you use these methods, you probably won't have many image quality problems, and the order in which you make your changes may become irrelevant.