Flat shooting is key
You might get lucky and ambush the caribou but it is more likely that
you will have a longer range shot from 200-400 yards.
You should make it a point to practice with your rifle to be able to
put your caribou down.
I have shot them with everything from 22-250 to 375 h+h.
The best bet is picking a gun that you are very good with and practicing a lot
with it.
You should also practice in windy conditions.
With all this said, sometimes you can get really close to them and even toll them in with a hanky.
Good luck and remember that summer practice leads to a full freezer.
Thomas