One person who frequently lost his temper, finally learned to control it with the following method:
Whenever he felt angry at someone, he would take a sip of water and hold it in his mouth for five minutes. Only after the five minutes passed would he criticize someone.
During this time his anger subsided and he was able to talk calmly.
Sources: Erech Apayim, p. 85; Rabbi Pliskin’s Gateway to Happiness, p.211