Making meringues that aren't "weeping" or "beading" or generally unsightly is one of the sensitive techniques in working with egg whites. The following are a few points to keep in mind to help you produce successful meringues.

1. Egg whites should be at room temperature to assure greater volume. Start beating them slowly and then gradually pick up speed. If you start beating too quickly, you will weaken the air cells that form.

2. When the whites are foamy, add cream of tartar and salt. The cream of tartar will help stabilize the foam. If you do not use the cream of tartar, the air bubbles formed will be thin and weak and the egg whites will collapse and lose volume. Use about 1/8 teaspoon cream of tartar and a pinch of salt for every 3 egg whites.

3. Add the sugar gradually, beating, but make certain that all the sugar is added before whites are too stiff. Sugar should be completely dissolved and when you touch the meringue with your fingers, it should feel perfectly smooth without a trace of graininess. If sugar is not dissolved completely, meringue can "bead" which is actually undissolved sugar forming a syrup.
4. To avoid "beading" 

a. make certain sugar is dissolved in the beating or 
b. use sifted powdered sugar (this has a small quantity of cornstarch and will help stabilize the meringue). 

5. Whites should be beaten just until stiff peaks form when beaters are lifted. If you overbeat, meringue can "weep" which is the accumulation of moisture (tears) between the meringue and the filling. To avoid "weeping" do not overbeat the meringue and of course, don't underbeat either. Beat just until stiff peaks are formed when the beater is lifted. The addition of 1 teaspoon cornstarch to each 3 whites can help stabilize the meringue.

6. "Weeping" can also occur if the meringue is not baked long enough. This can be avoided by spreading meringue on hot lemon filling. If the filling is hot, the bottom of the meringue will bake longer. Bake for 12 to 15 minutes in a 350-degree oven.

7. Spread the finished meringue over the warm filling in decorative swirls, and be certain that the meringue covers every bit of crust.

8. Bowls and beaters should be scrupulously clean without a trace of grease or yolk.

9. If a bit of the yolk happens to get into the whites, pick it out with a piece of shell. If any yolk is in the egg whites, they will not beat to proper volume. Separate one egg at a time in a cup and then transfer yolks and whites to separate bowls.