1. If you are tired/hungover/sick/not feeling well/angry then don't deadlift
2. If you don't have the time to do 3-5 warmup sets then don't deadlift
3. If you don't have time to rest at least 3 mins between sets then don't deadlift.
4. If you can't lift a light/medium weight with perfect form then don't try and go heavy.
5. If you aren't competing and under the instruction of a trained powerlifting coach then don't try and max anything. If you can't do 7 reps with a weight then you shouldn't be doing 5 reps. Likewise if you can't do 3 reps with a weight then you shouldn't be doing 1. Leave 1-2 reps in the bank.
After hurting my back (while being competently coached), now lifting uncoached, and without one of my goals being 'deadlift a big number to get a medal' -- I've dropped them from my routine. I just don't find the benefits necessarily worth the risk, in my specific case.