RagingRandy is correct...warmups are to get blood flowing and to get the body used to the weight...not to tire you out. Here is an example of how to warm up and do 3 working sets on the deadlift...for a max of approx 405lbs for a few reps.

warm up 135lbs for 8
warm up 225lbs for 6
warm up 275lbs for 4
warm up 315lbs for 3
warm up 365lbs for 1
first working set 405 for as many as possible (approx 1-4)
second working set 365 for as many as possible (approx 3-6)
third working set 315lbs as many as possible (approx 5-8)

P