I know that lifting sub-maximal weight prior to a max attempt will increase your max, but to much will tire you out. What is a good routine for warmup?
It’s hard to say, it comes down to the person and how much you need to be ready.
Shizen’s right. It’s something you’re going to have to experiment with.
I do two sets of ten with ~50% of Max. Then singles at 80% and 90%. Then I attempt my old max and my new target max. All my singles are done with five minute rest periods.
That’s just how it works best for me, though. I could probably cut it down a little, because I can always tell how I’ll do when I hit the 90% single. I know whether I’ll hit my new max or not.