First and foremost is pre-focusing. This is simply done but few do it. Pre-focusing simply means that you focus on an object, any object, that you think is the same physical distance from the camera to the subject prior to having to shoot. This was done in manual focus days so that with only a light touch of the focusing ring the subject would snap into focus. This same technique works killer with AF lenses because with a light touch of the shutter release, the lens grabs on and focuses on the subject. This really simple concept makes a world of difference in capturing a sharp image, especially when shooting action.
Next, proper hand holding and long lens techniques are essential. These techniques not only assure a sharp image by the lack of movement of the film plane, but also assure the AF sensor stays locked onto the subject. I receive many emails from folks stating their camera's AF system keeps searching. So far, the problem has always been pilot error, not maintaining the AF sensor on the subject.
Finally, panning properly in conjunction with pre-focusing, proper hand holding or long lens technique speeds up focusing. A smooth pan permits the AF system to lock on to the subject faster. Proper panning technique permits the system to stay locked on. And in conjunction with all of these, good contrast makes the AF system work at its fastest along with fresh batteries (in the camera and in the mind).
The weakest link in photography is still the person behind the camera. Refine and improve on that, and you will have no only the fastest focus, but the best images and the most fun!
