The same set of skills and techniques will help you nail 'the sports page' look: moving bodies frozen in mid-action with good background separation. With the following advice and a little practice, it won't be long before you're nailing shots of little Jimmy delivering a knuckleball.
Or capturing great backyard birds.
Or making the sidewalk tricycle race look epic.
I shoot all of these subjects the same way: with a wide-open telephoto lens with continuous autofocus in multiple shot, or "burst," mode. I prefer back-button focus (see below). My lens is either the Canon 70-200mm f/2.8L (sometimes with a Kenko 1.5X tele- or the Canon 400mm f/5.6L on my Canon digital and film SLRs, such as the Canon 20D and the Canon EOS 3.
With the lens set to maximum aperture either via metered manual or Aperture Priority mode, set it to the widest aperture. If you choose Aperture Priority and let the camera decide on your shutter speed, be sure to select an ISO that will yield you a shutter speed of at least 1/800 second. The faster the better.
The larger the maximum aperture, the more background separation you will achieve at a given focal length and focal distance. A 400mm f/5.6 lens at maximum aperture will have a greater depth of field and less background separation than a 400mm f/2.8 at maximum aperture. It is my general thinking that faster is better. However, faster is costs more, sometimes in the range of several thousand dollars for a supertelephoto, so find your comfort level of price versus performance.
Get a feel for the how lens's autofocus system tracks your subject before you fire the shutter. Try to keep the object you are following in sharp focus on the active AF point. Birds are a good practice tool for this, since their flight paths tend to be rhythmic and regular. Keep following your subject in the viewfinder until you feel that the timing and framing and action is right. SHOOT! Hold down the shutter button and keep firing, while you keep following the action through the lens.
Did you nail the shot on the first frame? How about the second? Did the play develop and the fifth frame in the burst turn out to be really intense? If so, congratulations, you nailed the sports page look! If not, keep practicing--you'll get the hang of it.
What’s back-button focus?
Many advanced amateur and almost every pro-line SLR and DSLR has the option for back-button focus. If I am using autofocus, I use this exclusively. Why? I want the camera to fire when I press the shutter button. Nothing else. All of my Canon EOS-series cameras are set to CF4, option 3 (shutter button/AE Lock button: AE/AF/No AE lock). In this setting, the camera will not search for focus, which costs valuable time in fast-changing action.
To focus in this mode, I hold the shutter button halfway down while in Continuous (AI Servo) focus mode. I do not want to AE lock accidently on the sky or the ground, or whatever else may be throwing off the meter when I feel I am close to the decisive moment.
It takes some getting used to, but after a couple of days it will feel completely natural. Back-button focus is popular among pro shooters because it’s a simple idea: it lets the shutter button control the shutter, and nothing else.