If you shoot in a jpg format, be sure to download your pictures from the camera and immediately burn them onto a CD before you manipulate them in any way.
Every time you open a jpg image file you damage the quality. Imagine how much you'd lose if you repeatedly save and reopen the same image.
Burning a CD insures that you can always have a copy of the original high quality image undamaged.
I learned all this the hard way.
