playing at half valve, or wind pattern (using just air, and no buzz) are also great- playing afterwards is a "celebration"
Simply play the piece as normal while doing either. The resistance caused by the half valve forces you to use your ears, and apply more pressure. With the wind pattern you will need to breath MUCH more often, but at the same time- playing normally afterwards is exceptionally easy. Always envision projecting your sound to somewhere far away.
Don't forget to keep your teeth open- that was a big thing for me. Makes for a fatter rounder sound that carries.