I was taught to walk up "behind" the animal and fire a shot high into the neck area. Shooting a deer in the head makes a real mess, and believe me there's nothing worse than trying to drag a deer by the horns and they come out of the skull! If you think there's a chance of the bullet coming back and hitting you, get back a bit farther and kneel down and fire, if your still worried use the big rock trick I guess.