Most club caddie masters hold an orientation/training session for prospective caddies prior to the beginning of the season. These sessions orient you both to the club itself and to the job -- where to stand, how to hold the bag, how to take care of divots, keeping clubs clean, tending the flagstick, etc. Don’t miss it. And don’t be afraid to ask questions when you’re there. It’s good to have the caddie master, who assigns loops, know your name. One of the most basic questions is, “Do you schedule individual caddies or is it first come, first serve?” That makes a big difference as to when you have to be in the caddie yard.
There are training films on the web that can help, too.