This is the recipe I've been using for sugar cookies. It dries nicely. After one layer dries you can put more on top, such as detail, outlines, etc.
I use powdered egg whites (merange powder) instead of fresh egg whites. I just follow the directions on the powdered egg white container, mix up the powder with water, then use that as the egg whites in the recipe.
Also, I use my stand mixer and mix it seveal times while sifting in the powdered sugar. I never use the whole 4 cups of powdered sugar.
Royal Icing
---------------------
INGREDIENTS
4 egg whites
4 cups sifted confectioners' sugar
1 teaspoon lemon extract (or vanilla or almond)
DIRECTIONS
Beat egg whites in clean, large bowl with mixer at high speed until foamy (use only grade A clean, uncracked eggs). Gradually add sugar and lemon extract. Beat at high speed until thickened. NOTE: When dry, Royal Icing is very hard and resistant to damage that can occur during shipping/handling.