The title says it all.
Stability is the key:
if you're standing straight, both feet planted firmly about shoulder width apart, the foot of your dominant eye nearest your subject you have a good start.
Imagine shooting a bow or a rifle. The aiming technique is identical.
Hold your camera firmly, but not in a death-grip.
Relax your shoulders and upper arms. Tension will cause you to shake and get fatigued.
Press the shutter release with your finger tip by just bending at the knuckle. Moving your entire finger can move the camera.... that can ruin your shot.
Oh yes... don't forget to breathe... I know, it sounds silly. But if you hold your breath for a few seconds your pulse will rise, causing your camera to move in perfect rhythm with your now bounding heart rate.
A little practice and this stuff becomes second nature.
Here's a vid by one of my favourite shooters. He covers much the same thing for those who can't endure walls of text, have /ADD/ADHD/ are impatient.