If you have trouble pressing the shutter button down without shaking the camera, reader Mujtaba shares a quick solution: just use your camera's timer.
If you don't have a tripod while taking pictures and can't hold the camera steady when you click the shutter release, try taking pictures with the timer on (set to something low, like three seconds). This helps alot, as it lets me recover from the shake after clicking the shutter-release, and hold the camera steady.
It's not a trick everyone needs, but for the twitchier among us, this is a great way to avoid shaking the camera when you press the shutter down. Photo by das_sabrinchen.