Be sure to measure your flour correctly. Over-measuring your flour is going to result in a dry, crumbly cookie. Read my full post on how to measure your flour correctly here. Use room temperature butter. By softening your butter properly (and here are 3 ways you can do that in a hurry!) will allow the sugar to punch tiny holes into the butter incorporating air into the dough. Cold butter won't allow this to happen. So room temperature, unsalted, and you're good to go. Don't forget to take those eggs out early too. You also need a room temperature egg as well. Remember you want your ingredients all playing along well together. So a cold egg and room temperature butter just don't play nice on the playground together. You'll end up with butter that starts to seize up in your bowl. My trick? Put your eggs in a bowl of warm water for 5 to 10 minutes and you're good to go. Flatten those cookies a bit. These cookies won't spread much, so you want to help them out a bit and flatten them a bit. I prefer the fork criss cross method, but even a quick flatten with the palm of your hand will do the trick. Have you read my post on why your cookies spread too much? Check it out here!