Slightly literary — typical pattern is X
的要诀是 Y 'the key to X is Y.' Compare to the more colloquial
窍门 (qiàomén, 'knack, trick') and the closely related
秘诀 (mìjué, 'secret recipe / formula').
要诀 emphasizes essential method;
秘诀 emphasizes that the method is hidden or special.