The deadlift is arguably the most effective exercise in existence. It works more muscle mass than any other lift - hamstrings, glutes, erectors, lats, traps, and grip all work simultaneously to move heavy weight from the floor. But because it loads the spine under heavy tension, technique errors can lead to injury. Learning proper deadlift mechanics is an investment that pays off for a lifetime of training.
Start with the setup: stand with the bar over your mid-foot, hip-width stance, toes slightly out. Hinge at the hips and grip the bar just outside your legs. Before the bar leaves the floor, create tension throughout your body: pull your shoulder blades back and down, brace your core like you're about to take a punch, and push the floor away with your legs rather than thinking about pulling the bar up. Keep the bar close to your body throughout the movement - dragging it up your shins is correct.
The most common mistakes are rounding the lower back under load, jerking the bar off the floor (which causes a back rounding), and allowing the hips to shoot up before the shoulders. Film yourself from the side periodically to check your position. Start light and add weight only when form is solid. Work up slowly over months and years - the deadlift rewards patience. There's no rush to load the bar if your technique needs refinement.