I got myself one of those very heavy clubs and I leave it in my car. When I get to the course, I swing it in the parking lot for a while to loosen up. Then I'll putt a little and split a bucket of balls with my playing partner. The main thing is, that heavy club is the key element to my pregame warmup. It's a great tool.
I'll usually take some range balls and slowly incease speed like said before I'm often a little stiff from running that morning. Then I'll take a couple clubs with a right handed swing and a left handed swing to do both sides of my body equally.
Il always get out to the golf club about 1 1/2 to 2 hours before my hit off time. I start by stretching and doing some loosening stretches. Then I will hit a bucket of balls, varying my shots, and from there its onto the putting green before hit off.