Use Image Stabilization
A monopod is designed to support the weight of the lens, providing a stable shooting platform. If the lens or camera you are using has an image stabilization feature you should use it. Combined with a monopod these features will go a long way to helping you achieve sharp pictures.
Use a Fast Shutter Speed
The less time the shutter is open for, the less time the sensor or film has time to record any camera shake. Monopods are a great help in reducing camera shake by supporting the weight of the lens. A fast shutter speed will also help in achieving pictures that are sharp.
Position of the Monopod
Position the monopod so the bottom is positioned against your foot. Doing this allows you to have a feel for the angle of the monopod. In fast moving events like sports, you may be moving the lens frequently, angling it up or down by tilting the monopod. Keeping it rested against your foot helps hold it steady.
Use the Camera Straps
Monopods are screwed into the bottom of the tripod support in the lens. It is still a good idea to keep the camera straps around your neck as well. While rare, it is possible that the bolt which screws into the lens tripod socket can break. Having the camera straps around your neck will prevent damage occurring if the monopod becomes free of the lens.