David Pogue's Digital Photography: The Missing Manual

Use the Self-Timer

Every camera has a self-timer mode. You press the shutter button, but the camera beeps away for 2, 10, or 12 seconds before it takes the shot.

This feature was invented, of course, so that you, the photographer, can frame a group photo, squeeze the shutter button—and then, in those 20 seconds, run around to join the other people, thereby getting into the shot yourself.

But here's a trick that probably doesn't occur to many people: Use the self-timer even when you're not trying to be in the shot yourself.

That way, you avoid any risk of bumping the camera, even slightly, in the simple act of pressing the shutter button with your finger!

During long exposures (slow shutter), zoomed-in shots, and close-up shots, even that little movement can blur the shot. But not if you use the self-timer.