Camera Shake, a leading cause of bad photos
Camera shake is like the gingivitis of photography. When you're dealing with camera shake you're dealing with images that are not in focus or are totally blurry. Most often with images that suffer from Camera Shake the image is just slightly out of focus.
Example of camera shake:
(photo by itchys)
Notice how the image is just barely out of focus but it's far enough out to ruin the image. The horror!
Why does camera shake happen?
When you take a photo there is a moment when the shutter is open and light hits your camera's sensor or film. If the shutter is open for a long time and you move your camera while it's open you will most likely get a blurry photo. While the shutter is open and you are holding the camera tiny movements in your hands and arms will make your image slightly blurry. In photography the shutter is very very fast so a long time in this context could even be less than a second.
There are a whole host of ways to avoid camera shake. Here are a few:
One method would be to shoot at a faster shutter speed. In some cases to achieve these higher shutter speeds you will have to shoot higher ISOs
Shoot at Higher ISOs
Obviously the side effect of this is that you'll get more noise and grain in your image but I'll take a noisy image that's in focus over a blurry image any day of the week.
Use a Better Lens
Another option would be to shoot with a faster lens. If you shoot with a better lens you can get away with more. So if all things are equal you can capture more light with a better lens. As such you'll have less camera shake.
Get a Better Camera
A camera with a high quality imaging sensor can almost always shoot sharper images in lower light. Before anything else gets written here I should note that 'getting a better camera' should almost NEVER be a solution to a problem in photography. I just needed something to fill out this list! In all seriousness though a better camera will help in this situation so get yourself a better camera.
Use A Tripod!
The most obvious solution is to just use a damn tripod! As a general rule you almost always get sharper images when you use a tripod. The tripod is a stable platform for your camera and it does not move and it will eliminate camera shake. Don't have a tripod? Go buy a tripod.
Hold The Camera Steadier
When you don't have a tripod or can't use one just take a moment and control your breathing and concentrate on being still. Take a deep breath or two. Compose yourself if you will.
Make a Tripod
You don't have to carry around your bulky tripod. You can just make your own tripod out of string!
Hold the Barrel
Support your camera by holding the barrel of your lens and putting your elbow on something like your knee or something solid.
Bring Your Elbows In
Bring your elbows in and rest them on your stomach/chest. That way you'll be making a tripod between your two hands and your eye pressed against the viewfinder.
Make it Art!
Just like most artefacts and technical screw ups in photography you can make it into an art form. People have taken this artifact of photography and produced some very interesting images. It's like the rule of thirds, you should really learn it before you start to break it as a rule.
Examples of camera shake (or motion blur) being used creatively:
photo by unukorno
photo by ninette_luz
To learn how to use motion and the blur effect creatively take a look at our article: How To Show Motion in Photography By Panning
Put Your Camera on a Stable Surface
You can really get away with anything that is stable and doesn't move. Just be careful because cameras have been known to fall of things you might have thought we're stable.
Lean On Me. And I'll be your friend
Just like Bill Withers suggests, just lean on something. If there is a post or a tree or something right at the position you want to shoot from then lean on it. This essentially removes a great deal of the movement that is occurring in your body all the time
Geting closer to your subject means you won't have to zoom as much. The less you have to use your zoom, the less your lens will shake.
Stop Drop and Shoot!
If you can lie on the ground. The all but eliminates the movement of your body and will result in sharper images.
A Simple Rule
As a really rough mental guideline ensure that your shutter speed is never slower than half the focal lenght of your zoom lens. So if you're shooting with a 300mm lens you don't really want your shutter speed to drop below 150/sec. This is an very very rough tool but it helps you keep camera shake in mind.
Now get out there and shoot some razor sharp images.