I ran across this article over at Lifehacker about using techniques that snipers are trained for even when taking photos. The example they had in this article was about the breathing-cycle used by sharpshooters to be as steady as possible in the moment of firing. By utilizing this technique also when taking photos you can reduce camera shake quite a bit.
So, the sniper is said to breath calm and normal. While taking aim, place the finger which is to be used to shoot on the trigger and keep breathing normal. Pre-aim as good as possible to keep a good view on what you are about to shoot. When the moment is approaching to take the shot aim during an exhale and squeeze of the trigger during the breath so that you finish off just before you need to breath in again.
To apply these rules to a photographer you just have to do exatly the same with your camera which was described with a weapon. Locate your target in your viewfinder, squeeze of the trigger during an exhale and have the photo taken just before your breath runs out.
At first you may feel a bit silly to practice this technique but after just a litle while you may feel it to be a quite natural way to take photos. And by getting it as your normal way of taking photos you will see that even your normal freehand photo-sessions may increase in quality.
I wrote another article about reducing camera shake a little while ago, read it through for more tips!