Load the bar up with the appropriate weight
Put the bar on the ground, and bend over and grip with either a palms facing you grip, or an alternating grip (one palm facing in, one palm facing out). Your grip should be just outside of your legs.
Bend your knees slightly, and start with your feet about hip width (15 inches or so apart). Your toes should be pointed out. Your hips should be higher than your knees (not low like the bottom of a squat)
With your butt out and your back tight (not rounded), look forward and roll the bar to your shins. Pull the bar up by driving through your heels and standing up making sure to keep your lower back tight. do NOT lift with your arms. The bar should stay on your body the whole time (see pic below)
Stand all the way up, and then return the bar to the floor in reverse order. Do not just lean over and bend your back to set the bar down!
Common Deadlift Mistakes
Rounding the back - This is the most common mistake. People have a tendency to round their back when starting. Rounding the back is a major mistake and can lead to serious injury
Pulling with the arms - The deadlift should not involve your arms pulling at all. The arms merely stay connected to the bar, while the legs and the back do all of the lifting.
Butt too low when starting - Many people make the mistake of putting their legs and butt in a low squat position. When starting your butt and hips should be higher than your knees.