Beyond The Camera
It could be said the photo can be taken a second time on the computer!
A PC auto correction could correct your photo in one click.
Tight cropping can help remove unwanted objects from the image.
Cropping for a better composition can easily be done on a PC. Remember that if the image needs to be printed at a later stage then the cropped image aspect ratio needs to match the paper to avoid big white boarders to one set of sides or more unwanted cropping in the printing process.
Groups. By taking more than one image at a time, if someone blinks or looks not quite right then swap their eyes, face or head from another image on the PC.
By taking photos in colour you have the choice to keep them in colour or change it or some of it to black and white on the computer.
Remove spots and blemishes.
Whiten eyes .
Smooth out lips.
Reduce lines under eyes.
Colour hands or skin in general to match face foundation or just colour to look tanned.