Mark Schubin, a television engineering consultant, recommends starting your calibration by adjusting the brightness level. Starting at the lowest setting, gradually increase the brightness of the screen until just before the darkest points on the picture begin to brighten.
The best tip for finding the proper contrast is to freeze-frame your screen with a mostly white image, such as a glacier or a screenshot with a bright white shirt. Start with the contrast level all the way up, then gradually reduce the setting until all of the details in the whites emerge.
For color, the best way to calibrate properly is to find a screenshot of a human face. Start by turning the color all the way up until the person looks sunburned. Then gradually lower the color until the skin appears realistic and natural.
The sharpness setting will control how little or how much the edges of different images are noticeable. This is highly personal preference, so toy with the settings, starting at the lowest setting and going up, until you reach a level that suits your eye.