As a general rule…
every photographer edits his or her photos to some extent. Sure once in a while a shot here or there will turn out just fine from the start but that’s pretty rare. And while most serious photographers use a program like Photoshop to make adjustments to their photos, the tips below will apply to just about every possible editing tool.
Let’s think of it this way:
Hollywood celebrities and those with substantial incomes who spend a lot of time in the spotlight sometimes get a little “work done” aka plastic surgery. However, sometimes it’s done well and other times it can be a horrific disaster. The same can be said for these two approaches to re-working your images.
1. Exposure
Say you take a picture you love but notice that the image you bring up on your computer screen is darker than you had hoped. What’s a shutterbug to do? – why, bump up the exposure of course. Not so fast! While this is an easy and effective technique, you have to be careful. If you turn up the exposure too far, the washed out effect that will result can look unappealing and amateurish. Unless you are going for an intensely blown out scene intentionally for artistic purposes, this is a very bad idea.

Blown out shot from excessively high exposure.

A well exposed photo from my work with Three Rivers Creative Arts.
2. Saturation
Having the pleasure of working with a number of alternative models, I know that photographers like myself love to showcase subjects with colorful hair or body art. When attempting to do this, or to enhance colors in less than vibrant skin, muted sunsets, animal coats or anything else, you might opt to increase the saturation. Again, good idea, but keep it to a minimum. While a little saturation can add some wonderful coloration, too much can actually bring out the noise in a shot, redden this skin too much in people and simply make things look less realistic.

Unrealistic looking shot resulting from excess saturation.

One of my well saturated shots from a shoot for Twisted Angels.
The bottom line:
No matter what the subject matter might be, the same rules apply – by all means kick the exposure and saturation up a notch, but be careful about how much.