My general principles:

• always work on a copy of your image
• work on your best images - don't waste time editing all of them, just the ones you want to share/print/pulish
• work non-destructively where possible (RAW editing, using layers, save intermediate steps if necessary)
• when you are done, you image shouldn't look "edited"

Back up your files

Before you edit, make sure you have the originals backed up, so you only work on copies. Copies of your files should ideally be on a 2nd hard drive, external drive, CD/DVD, and if possible stored in a different location in case of fire, flood or theft.

What method is best to take backups of your digital photos?

Culling Process

Go through your images and flag or even delete the obviously bad ones (out of focus or otherwise). Use some sort of ranking system to arrive at what your best images are, and concentrate on editing and sharing those. Some people may cull their bad images out before backing up, so save space.

What's a good strategy for choosing which photos to keep?

Non-destructive RAW editing

Using a tool like Adobe Camera Raw (in Photoshop or Lightroom), make global adjustments to:

• White Balance (overall warmth/coolness of the image)
• Exposure, contrast, blacks/whites
• Color, saturation and vibrance
• possibly some pre-sharpening
• initial noise reduction
• rotation and straighting

These changes may be all you need to do, and they are non-destructive (you can go back and undo/redo them. If you shoot JPG, you still make the same adjustments, but the changes will not be completely reversable, so you may want to Save As a copy once you're done.

Local editing

Next, depending on the image you may need to do further local adjustments, for example:

• spot removal - removing dust spots or anything else small and distracting
• remove color casts
• dodging and burning (using dodge/burn tools or curves/levels layers with masks)
• landscapes - you might use gradients to darken skies
• portraits - skin smoothing and retouching

Effects

Once any defects are removed and the overall color and contrast are good, you may want to do conversions or effects (these could also be done earlier in the workflow)

• conversion to black and white
• special effects actions or filters

Output

For printing, uploading to the web, etc. you'll need to

• resize appropriately
• crop (you may want different crops from the same image for different purposes)
• final output sharpening - depends on if you're printing, saving to web
• select color space
• you may want to add a vignette or digital frame/border