I run only medium distance (5K to half-marathon) road races, and my routine is pretty simple.
After parking car at race, walk for 10-20 mins to warm up (while collecting race number, etc.). Bathroom. Go back to car, apply Body Glide to body, Vaseline to feet, tie hair up in pony tail, switch from driving/walking shoes to road racing shoes.
Starting 20-40 mins before race, do a warmup jog/slow run at a distance that varies from 3-4 miles (for a 5K on a cool day) to 2 blocks (for a half-marathon on a warm day). Bathroom again. Stretch lightly.
Go to starting line and run.
After race, DO NOT sit down for at least one hour after finishing. Walking a lot is good, standing is OK.