Football

I played linebacker, 50+ years ago, and the quality of tackling in the NFL absolutely appalls me. College is a little better, but not much.

Head up, feet still in contact with the ground, contact made with your shoulder above the knees and below the shoulders, wrap your arms and drive with your legs through the hit. You are still looking at the ball carrier when you hit him, and you are looking right into his eyeballs when you have him on the ground. You smile at him and you do not help him up.

One additional point, when you lower your head to hit with your helmet, you are looking at the ground. Hitting the ground is not useful, and when you are looking at the ground that is most likely what you are going to hit. You very seldom hit what you are not looking at, which is why pro football player miss more tackles than they make.

The same thing applies to launching yourself through the air to make a hit like a ballistic missile. "Ballistic" means "no longer guided." As soon as you leave your feet the runner changes direction and there you are, flying gracefully through the air like a ballet dancer and hitting nothing, while the ball carrier prances down field past you, making you look like an idiot. Keep your feet on the ground and your momentum under control and when the ball carrier changes direction so do you.