要诀

要诀	yào jué	the key trick / the secret of success
要	yāo	(bound form) to demand; to coerce
要	yào	to want; to need; to ask for / will; shall; about to / need to; should / if (same as 要是) / (bound form) important
诀	jué	to bid farewell / tricks of the trade / pithy mnemonic formula (e.g. Mao Zedong's 16-character mantra 十六字诀 on guerrilla warfare)