Shutter speed is  important as it is one of the variables that determine  the sharpness of your image along with exposure and aperture (depth of field). The shutter speed is especially important with action or moving subjects. The faster the movement, the faster the shutter – for example; someone jogging 1/45-1/60 sec, car at normal speed 1/125 sec approx. Motorcycle / car racing 1/250+ sec. Panning is moving the camera in the direction that the subject is going, this has two benefits; it reduces the shutter speed and blurs the background while maintaining a sharp subject. This also works well where you  might have a distracting background or many spectators.

Always make sure that you have the correct shutter speed for the appropriate lens or zoom. As a simple rule try to have the same shutter speed or greater than the lens length. Example 17-40 zoom use 1/45-1/60 sec, 200mm zoom use 1/250 sec. With special anti-shake  lenses you can use these lenses with 2 0r 3 stops less depending on the brand or make but you pay a premium for this feature on most lenses. Experiment and you will quickly  find out how low a shutter speed you can use. Also don’t be afraid to increase your iso up to400 or 800 iso if the lighting is poor as many digital cameras have good results up to 800 or more in some cases. If lighting conditions are good use the lowest iso usually 100 as this will give the sharpest results.