1. correct form - most injuries from deadlifting (or lifting anything) come from using too much back and too little leg drive - keep your lower back straight/arched - use assistance exercises like romanian deadlifts in higher reps to condition the spinal erectors
2. gradual progression - start light and add weight slowly, stay away from 1RM attempts or going to failure
3. flexibility - do a lot of stretching, before and after and on off days