Without the right equipment, even the best photographer's going to turn in work that robs a slam dunk or a slide into third base of the excitement and action of the moment. Is the shot out of focus? No good! Zoomed out too far? That's a waste, too. Buying good lenses is the first step. Having them on hand and instantly available is the second.
Sports photographers recommend a finding carrying solution for lenses and other gear like SD or Compact Flash cards, batteries and add-on flashes. Photography gear companies sell bags, vests and belts made to hold everything professionals need on the field. Sites like OutdoorPhotoGear and B&H sell a range of accessories, from large bags to single-lens pouches. Accessibility is key in an equipment setup -- every second you spend fiddling with a lens change is a second you could be snapping pictures.
Beyond lenses, having backup cards for extra photos and battery packs for long shoots is always a good idea. A monopod or tripod (check with the venue to make sure your tripod is allowed) is also vital for shooting with a telephoto -- long lenses are far too bulky and heavy to hold steady for long periods of time. Once you're equipped to cover a sporting event, it's time to get down to business: exploring what goes into a great sports photograph.