Warmups depend somewhat on your conditioning level. You have to be able to hold your warmup and the higher conditioning, the longer you can hold your warmup.
FOR A WORKOUT:
3-5 X progressively faster strides. I use one of the old San Jose Speed City drills, which is high knees progressing into leg extension.
3 X standing long jumps (30 sec rest)
15-30 min rest for potentiation, then start workout
FOR A RACE (finals only, no prelims and not at altitude):
.......day before:
3 X progressively faster strides.
2 X standing long jumps (30 sec rest)
15-30 min rest for potentiation, then 2X30m block starts
.......race day:
3 X progressively faster strides.
35 min rest
2X40m from blocks, 35 min rest
RACE
My race day is actually from Ato Boldon, but he didn't mention the pre meet day and he did mention 2X70 rather than the 2X40 which works best for me. One again, the rest length depends on your conditioning level, and beginners at sprinting often can't hold a rest or warmup more than 10 minutes without losing performance.