If you're anything like me, when a big buck comes in close, your body is going to be sizzling with adrenaline. Your brain cells are going to stop firing, so your instincts are going to have to take over. It is hard for anyone to keep their composure when a big buck is headed their way, but if you have a predetermined plan of action, you're going to do all right.
The biggest mistake you can make when a buck is coming towards you is wait too long to draw your bow. You may be afraid to move, or you may even be a little paralyzed from buck fever. But you need to snap out of it and make the conscious decision to draw your bow.
If a buck is coming in fast, I want to draw my bow early so I'm ready for anything. I draw the first chance I get when the buck gets into shooting range and then I hold until he presents the first good shot. Once I'm at full draw, I can make a quick shot if the deer gets spooky.
Take the first good shot; it may be the only one you get. A lot of bowhunters make another mistake by waiting for the perfect shot -- but the perfect shot rarely presents itself in the real world. Don't force things, but if the animal's vitals are exposed and you know you can make the shot, stop waiting and start squeezing.
If you follow a predetermined plan of action for incoming bucks, you're going to put more meat on the table.