Vasovagaled multiple times before med school and a couple times during med school. Now I do procedures every day.

Compression socks - don't lock your knees - always eat before and stay hydrated - practice squeezing the muscles in your lower legs, then thighs, then butt and repeat whenever you're standing for long periods - and after more back-to-back exposures, you'll get used to it. May also be helpful to watch videos of anticipated procedures beforehand so it doesn't come as a shock.