Rule #1 for getting sharp shots is using a shutter speed appropriate to the focal length of lens you're using. The basic formula looks like this: Shutter Speed = 1/focal length. So if you're using a 60mm lens, the minimum shutter speed should be 1/60 of a second, a 200mm lens should be around 1/250 sec, etc. The wider the lens, the less you need to worry about it, so if you've got a fisheye lens, go ahead and shoot it at 1/15 of a second hand-held. Note, if you have a lens with Image Stabilization or Vibration Reduction os some similar technology, that usually buys you an extra 2-stops of shutter speed. So lets say you're using a Canon EF 100mm f2.8L IS USM Macro lens, you would normally need a 1/100 of a sec, but if you switch on the IS, you should be able to do it at 1/25 sec.
Rule #2 Use your tripod. Nothing gives you a steady shot like locking your camera to a tripod. Here's Harriet the Hummingbird in her nest; its the same basic shot, except the first one is hand held, and the second one is locked down to a Gitzo Mountaineer Mk2 G1325 tripod with an Arca Swiss Monoball head. Both are shot with a Canon 135mm F2L telephoto lens, ISO 100, 1/125 sec @ f2.8.
Rule #3 Stop down 2 f-stops. Fast lenses are great but they are not optimally sharp wide open; nearly all lenses have a sweet spot of sharpness, which is 2 stops down from full aperture. What happens in those two stops? The added depth of field reduces most of the distortion you get at maximum aperture, including reducing vignetting. Here's the same 135mm lens as above, but I photographed an Adobe Lens Calibration chart so you could really see the difference. The first one is 1/500 sec @ f2.0, the second is 1/25 sec at f4.0. Caveat Emptor: stop down too far, and you start generating a different kind of distortion that will degrade your images.
Rule #4 Use your flash. Most on camera flashes have a very short flash duration, 1/1000 or 1/2000 second. So if you overpower ambient light with flash, that's the equivalent of shooting at that shutter speed. A hummingbird's wings beat at 60 times per second, so you will need a really fast shutter speed to capture the wings without a blur, but you can always do the same thing with a flash, here the exposure was only 1/160 sec at f2.8 with a Canon Speedlite 580EX II Flash:
Well there you have it, the top four ways to shoot sharper photos, the real trick is to balance all these techniques based on the specific situation; e.g. when there's not enough light, are you going to compromise two stops of aperture, two stops of shutter speed, or maybe two stops if ISO?. One last Caveat Emptor; all the above being true, sharper is not always better. Sometime a not having everything tack sharp is good too, so don't go crazy chasing the holy grail of sharpness. Sometimes you might want even to shake the camera for effect, or use a Holga (but with flash and on a tripod :).