The best and the worst exercise ever. Best when it's performed correctly, and worst when you see it mistreated. I've included a couple of different videos here. If you think your technique could do with some refinement, it probably does. If you think you're already deadlifting well - you probably could still benefit from these tips. When we talk about human movement and movement patterns, the one that is performed most often (besides walking) is bending, and it's also the one with the highest chance of injury if performed poorly. Prepare to banish back injuries forever by perfecting your deadlift.
Ignore the fact that this video is aimed at 'dudes'. The tips are suitable for all lifters.
If you feel you need a little more cueing on your set up position this video goes into more detail. One of his tips is to remove your shoes - a good tip if your shoes have a heel - but if you are wearing a flat sole you can keep them on.