Nothing personifies the American West like the cowboy. The image—of a weather-worn man, in jeans, cowboy boots and hat, riding his horse on the open plains, swinging a lasso, herding cattle, or enjoying an evening cookout by an open fire—is woven through the last 150 years of U.S. history. Fortunately for photographers, the cowboy is alive and well, working on ranches around the country. There are working ranches where cowboys tend to their herds of cattle, and "dude" ranches that specialize in teaching horseback riding to anyone with the curiosity to learn, and offer "city folk" the opportunity to get their hands dirty helping out. If you ever have the opportunity to visit a ranch, do so, and bring your camera, as you'll be able to make great photographs, reminiscent of a bygone era.
When shooting action shots of cowboys, horses or cattle on the move, and especially the action of a rodeo, you'll want to use a high shutter speed, at least 1/500 of a second, to capture the action. Use the shutter priority mode to set the shutter speed, and the camera will choose the corresponding aperture for the correct exposure.
Probably the easiest photos to shoot will be those of the cowboys at work. Keep the usual things in mind: an interesting subject, clean background and good exposure. The cowboys often will be working with horses or cattle, so keeping a safe distance outside the corral or fence is important—these are wild animals. You can use that fence several ways. Try climbing up on it for an elevated view (being careful not to get hurt). That will provide a different angle while pushing any bright sky well above your subject. Fences also work well as framing devices. Try shooting through them, but leave part of the rails in the frame, either at the top, the bottom or both. Having them there will help guide the viewer's eye to your subject.
Then see what happens if you put your camera down low. A low angle, especially when photographing a large animal like a horse, can make it appear even more magnificent. And if there's a blue sky, you'll make it more prominent as well. You might want to try putting your camera on the ground and tilting it up, guessing at the framing. Because you're shooting digital, don't worry if it's not perfect. Fire off several shots in succession, and as you're doing that, move the camera slightly, up and down and left to right. Do that enough and at least one of those frames will be just the way you want it. Then you can delete the ones that didn't work.
Make sure you get some variety by shooting tight shots with your telephoto lens too. The cowboys may be roping or working on animals, so zoom in and see how tight a shot you can get.
Always keep an eye out for interesting details or close-ups of gear and clothing. Spurs, belt buckles and ropes all make good shots. Ask where the tack room is and if you can go in there. That's where much of that gear is stored. If you have a Micro-NIKKOR lens, try shooting more abstract images that show just the texture of the rope or worn leather.
Of course, cowboy portraits can be fun to shoot, too. As with any portrait, the background is important. If it's sunny, try to find an area of open shade, or stand your subject just inside a barn. The light coming through an open door will be softer and more pleasing than the bright sun. You will probably want to use a little fill flash to balance out the exposure in such a situation.
When you've finished taking pictures, be sure and repay the cowboys' courtesy. Offer to send them some digital files or even prints. It's a nice thing to do, and the next photographer to visit will benefit from your kindness. After all, everyone should get a chance to photograph cowboys at least once.