I have found warm up for me is more mental than physical. Stetching helps, sure, as you're going to be active for the majority of the day. Other than that, I putt a few at the practice basket to make sure everything "feels" right; I try not to putt to much. The last thing I want to do is string together a bunch of canned or missed putts and then player's meeting gets called. If there's a particular hole that I'm psyching myself out on, I might walk over and throw a few drives on it.
I really don't like to warm up too much. If I'm getting there early, it's to get a good parking spot; not to work some stuff out before the tournament. You had your entire life to figure it out; I don't think a half hour of practice before the tournament is going to drastically change your score. But that's just me.