Very good points brought up here! Knowledge of the game you are hunting is very important! The more you know about the habits of the whitetail, the better you will become as a hunter.
Learning to scout and read terrain and deer signs are also crucial!
I've seen it time after time, where hunters get off of leases that I am just getting on, saying that there are not many deer on the property. Then when I hunt the same areas that they gave up, I see deer!
So, again I'll stress that the knowledge of your game and ability to read the signs are the most important things!
Remember, the best shooter in the world can't kill 'em, if he can't find 'em!
And as Bob said, "patience!" That helps a lots too!
Good luck!