Make sure your bowl and whisk are clean and that you haven’t accidentally allowed any of the egg yolk to mix with your whites. The tiniest foreign particle will keep your whites from whipping. It’s also better if you have time to bring your egg whites to room temperature. Room temperature whites will whip up easier and with more volume.
A well-whipped meringue should be completely smooth and shiny.There are three basic types of meringues, French, Swiss and Italian.
French meringues are made by whipping the egg whites until they’re foamy, then adding sugar. For Swiss Meringues, the egg whites and sugar are whipped over a pot of boiling water just until the heat dissolves the sugar. (Make sure the bottom of the bowl doesn’t come into contact with the boiling water or the heat will scramble your eggs.) The whites are then whipped until they’re full and glossy.
Italian meringue is a little trickier. The egg whites are whipped to soft peaks while sugar and a little water are cooked until they reach 238 degrees Fahrenheit. The sugar syrup is then poured into the whipped egg whites while the mixer’s still running. Try not to pour the syrup onto the beater or whisk. The syrup will cling to the whisk and solidify before it’s incorporated into the whites. Italian meringue is the most stable meringue, meaning it’s less likely to fall or collapse as it sits.
You can give your French or Swiss meringues more stability, so they’re less likely to shrink or collapse, by adding a pinch of cream of tartar or cornstarch to your egg whites.