Any trace of grease in the whisking bowl will prevent the egg whites from rising properly, so wash it out before use with very hot water and a drop of detergent or wipe with a little vinegar. Dry the bowl thoroughly. Whisked egg whites should form slightly soft peaks. If the whites are beaten too much, they will be dry and will not fold well into the sauce.
The classic cheese soufflé recipe can be cooked in individual ramekin dishes instead of one large dish: place the ramekins on a baking sheet and cook for about 12 minutes only. Individual unbaked soufflés can be frozen in freezerproof ramekin dishes but add an extra egg white when whisking. Thaw at room temperature for 1 hour, then bake as usual.