Use heavy-gauge aluminum baking sheets. Thin, flimsy cookie sheets translate into burned cookies. My favorite baking sheets, sometimes called half-sheet pans, are rimmed and measure about 17- X 12-inches.
Parchment paper is the cookie-bakers best friend. Parchment paper turns any cookie sheet into a nonstick pan. It holds up much better than waxed paper at high temperatures. Even if a recipe doesn't call for a greased baking sheet, get in the habit of lining the sheet with parchment every time--you will only have to change the paper between batches, and skip the washing.
When baking two sheets at the same time, switch the positions halfway through baking. For the best results, bake the cookies one sheet at a time in the center of the oven, but most cooks like to speed things up and bake two sheets at a time. To ensure even baking, switch the positions of the racks from top to bottom and front to back halfway through baking. This is especially important in electric ovens with top-heating elements.
Let the baking sheets cool between batches. If you put cookie dough on a warm baking sheet, the dough will melt and spread before it hits the oven. Not good. If the weather is cool, place the baking sheet near an open to help it cool quickly. Don't run cold water over the baking sheets to speed things up, as you run the risk of warping them.
Buy airtight containers early in the season. Old-fashioned cookie tins do a great job of keeping cookies fresh, but if you delay purchasing them, you could find yourself shut out. I have used new plastic storage containers (they come in many different sizes) instead with much success, but I have now marked my calendar to buy decorative containers in October.
Store each cookie batch in its own container. Don't mix cookies because they can transfer flavors. Also, moist cookies can soften crisp cookies and vice versa. If you combine cookies to make a gift assortment, separate the layers with waxed paper.