Technique -The Principles of Steady Photos
A camera is just a light-tight box containing a light-sensitive material, be that film or a sensor. The aperture in the lens is the hole that the light enters through, and the shutter speed is how long this hole is left open. If there's not much light or you're using a smaller aperture, then the shutter will have to be open longer to gather enough light for the correct exposure. In that time it's likely that the camera (and probably the subject too) will move slightly. This results in motion-blurred photographs. You can tell motion blur because it's directional. If other parts of the photo are sharp and your subject is evenly blurred then it's likely you need to check your focus instead.
To get properly sharp photographs, a sturdy tripod is needed to keep the camera steady, as well as a subject that's completely still; or a high-powered flash that allows the entire exposure to be made in one rapid burst of light. However, while the ability to scrutinise photographs pixel by pixel on a computer can be useful, concern for sharpness shouldn't put limits on your photography. Most camera shake isn't noticed because the photos aren't enlarged sufficiently, and intentional blurring of elements within a photograph can set it apart from a shot that's technically perfect but uninspiring.
It used to be that you could take the minimum 'safe' Shutter Speed to be 1/(Focal Length) but this is outdated, as you can immediately check for sharpness and learn your own limits. In addition, image stabilising is built into a lot of lenses and even camera bodies, giving you an extra few stops leeway. But, practice keeping the camera still when you're photographing and you'll be rewarded by being able to get usable photographs in lower light conditions.
The range of postures that are crucial for supporting the camera are readily available online (here at Photo Answers) so have a look at these first. Since there are a lot of similarities, I'm going to go over the principles of marksmanship, as applied to photography. I've substituted 'weapon' for 'camera' and elaborated where necessary;
1. The position and hold must be firm enough to support the the camera
This requires a balance between holding the camera too loosely and gripping hold of it too hard, both causing it to shake when you press the shutter. If you hold the camera too tightly, the disturbance from your heartbeat and breathing will travel through your skeleton. Practice until you get the right pressure.
2. The camera must point naturally at the target without any undue physical effort.
If you look through the viewfinder and relax slightly, you will find that the camera will want to point in a certain direction. Normally, you can reposition it with your wrists, but this will put a slight strain on your posture. Try moving your whole stance, maybe bringing a foot back further or putting your legs further apart for stability. Make adjustments until the camera naturally points towards the subject without any tension.
3. Sight alignment and sight picture must be correct. Breathe!
Breath control is the most vital part. First take several deep breaths to take in more oxygen. Now breathe normally, if a little deeply, while looking through the viewfinder. You'll notice that it should rise and fall. Avoiding any tension, you'll want to take and hold a half-breath, capturing the photograph within a maximum of 5 seconds; any longer and you'll lose the advantage.
4. The shot must be released and followed through without undue disturbance to the position.
If you jab the shutter button, the camera will move. At lower speeds, this will blur your photograph. Therefore, gently put increasing pressure on the shutter button until the photograph is taken. This should be very smooth to ensure the sharpest picture possible. Again, practice what works for you.
As you put these techniques into use with your photography, you'll become more confident in using lower shutter speeds, opening up a whole world of creative possibility. You'll learn to see which parts of a scene are likely to blur, and by how much, at specific speeds. For example, in this photograph that was shot on film, the stationary foot is sharp but the moving legs are blurred;
In this photograph of Maxi Jazz from Faithless, I'd already got the 'straight' shots, and wanted to capture a more mysterious look as a nudge towards his interests in spirituality. Determining where the photograph was likely to be reproduced and therefore the acceptable amount of blur I could use to create atmosphere gave me the shot below.
Since you're effectively guessing how the subject will move, you cannot be as sure about getting a good photograph. However, this uncertainty opens your photography up to the serendipity of a great one. And the more you practice and pre-think your shots, the more you'll great ones you'll get.
When you have control over sharpness you can start panning the camera with a moving subject and adding small flashes to freeze certain parts of the action, intentionally blurring part of the photograph to remove distracting details, change the mood, or blend colours.
Start looking more closely at the movement around you too; how fast people's feet move compared to their shoulders for example. Make a mental note, or if you have a digital camera with you, take photographs just to test your theories. You'll be surprised by how quickly all of this becomes second nature. Whatever you do, remember it's all made possible by a solid base.
Let me know if you've got any comments, or would like a specific technique explained at ben@benevansphotography.com, or here 
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(C) Ben Evans 2010 : All Rights Reserved : Let me know if you'd like to use the photos!