Baseball Cookies with Royal Icing
Lemon juice can be used instead of vinegar to wipe down equipment. Wiping down the equipment can help remove trace amounts of grease that will prevent your icing from whipping properly.
Place wooden spoons on either side of your dough while rolling out to guide your rolling pin. They will help you roll out the dough to a nice even thickness.
Placing parchment paper on top of dough while you roll it out allows you to roll out dough without adding additional flour. Adding too much flour can make the dough tough, and can create little pockets of flour in the dough that cause bumps to form on your cookies during baking, making it more difficult to decorate later.
Make the best use of the dough you've rolled out. Every time you re-roll the dough you add a bit more flour, and can create the flour pockets mentioned above.
Only put cookies of similar size on each baking sheet. If you try to bake smaller cookies with larger ones the small ones will be over done before the large ones are baked.
Chilling the cookies prior to baking will ensure they keep their shape while baking.