1) Increase your ISO. ISO 100 does give you nice clean images but if your shutter speed can’t keep up with the movement in your photo it won’t get you a sharp shot. Bump the ISO up to a comfortable, usable level for your DSLR. This will allow you a higher shutter speed and a sharper image. The lower your ISO the better your images will look but you want to sacrifice ISO in favor of a fast enough shutter speed.
2) Love on the shutter button. Camera shake is an issue when you want to create a sharp image. Squeeze gently on the shutter button and press it down calmly. Don’t mash the shutter button! It’s even better if you can trigger your camera remotely.
3) Shoot on a Tripod, if you don’t have a tripod use a makeshift one. Balance the camera on a fence post,a sturdy rock etc. Tripods are inexpensive and one should be in your car at all times.
4) Find your lenses “sweet spot”. Lenses have different sharpness at different apertures. Experiment with the lens you are using to see what aperture settings are the sharpest. This is generally around f8 but it varies.
5) Make sure you are shooting fast enough. Shutter speed is a giant factor in a sharp image. Shooting sporting events can help you to learn this quickly. If you want to freeze a golfer mid swing you need a very quick shutter. A rule of thumb some photographers use is your minimum shutter speed should be equivalent to the focal length of your shot. If you are zoomed in at 200mm the slowest you should be shooting is 1/200 of a second. If the shot is at 100mm you should be at a minimum of 1/100 of a second. I would recommend you go higher if sharpness is important in your photo. The golfer mid swing you need to shoot over 1/2500 of a second to really lock him or her in place sharply.
6) The quality of your lens will directly affect the sharpness of your shot. You get what you pay for when it comes to lenses in most cases. Often prime lenses (fixed focal length lenses) are sharper than large zoom lenses. Having said that there are some very sharp zoom lenses out in the market these days. I love my Nikkor 18-200 VR lens as an everyday walk around lens. Kit lenses can take sharp images but you are better off replacing your kit lens with some nice glass. Many people buy a DSLR for thousands of dollars and then don’t spend money on some nice lenses. The quality of your lens can have more impact on your overall image quality than the camera body and the sensor inside.