Using CMYK and RGB
Here's a great explanation of CMYK for those who do RGB.
Rule Number One, above all else in print, is that what you see on paper will not look like what you have on screen.
This doesn't just apply to professional printers. Do you use a color laser printer? You probably already print in CMYK. Depending on your print driver, your print job may be sent to the printer in RGB, but the ink you're using is probably Cyan Magenta Yellow and Key (black). If you're doing design work, switching your print driver to allow for printing in CMYK may give you more reliable and controllable color. This might also improve other aspects of your printing as well. The postscript drivers that allow for CMYK printing can also improve the sharpness of vector graphics in your printing. Go take a look at the article at Mezzoblue