First thing is have a good range finder and build a very accurate range card. Bullet placement is where its at. Can you practice enough to squeeze the trigger until the trigger brakes without closing your eyes and jerking it. At long range especially that is utmost important. When the shot goes off your eyes should be open, if not shoot and shoot more and it will fall into place. Do that and everything else will fall into place. Just saying.
By the way, that 300 PRC is an awesome cartridge. Check out the 33XC first and then you will really be confused. Good luck.