1) Knowing how to mount a rifle. Lots of guys FIND game/target in the scope, WRONG way to do things.
2) As Ingwe said, quick is best. You can't be standing there for 10 seconds (see #1). You don't have to be quick draw, bring rifle up, find the spot (you should be close if you know how to mount a rifle) and shoot.
3) A good trigger HELPS much
4) I prefer a rifle with a little weight out front, or at least neutrally balanced. A butt heavy gun sucks for offhand.
