I train deadlifts by using the lightest possible weights and doing 2 sets of practice reps. Focus on keeping the spine stable, use legs to push the weight up. Don't add weight until you video record yourself and ensure your back and hips are on point. Back needs to not bend, and hips need to thrust forward, bar path vertical, close to the body as that's our center of mass. Ensure your sternum stays on the same plane as your stomach and neck, keep the upper back from rounding.