You whip cold egg whites

THE RESULT: Meringue doesn’t form, cake layers fall flat, soufflés have no lift.

THE FIX: Properly beaten egg whites are voluminous, creamy, and glossy, but they require care. First, separate whites from yolks carefully; a speck of yolk can prevent the whites from whipping up fully. After separating, let the whites stand for a few minutes. When they’re at room temperature they whip up better than when cold. Whip with clean, dry beaters at high speed just until stiff peaks form—that is, until the peak created when you lift the beater out of the bowl stands upright. If you overbeat, the whites will turn grainy or dry, or they may separate. When the whites are perfectly beaten, gently fold them into the cake batter or soufflé base. Otherwise, you’ll deflate them.