[header] How to bake cookies [title] Keep everything cold. [step] If you are using butter in your cookies (and even, to a certain degree, if you aren't) you will want to keep your ingredients refrigerator-cold. This will make your cookies much more firm and keep them from spreading out in the oven. 
[substeps] This means that you'll have to warm up the butter enough to work with it by placing it on the counter, rather than in the microwave. Absolutely never melt it in order to mix it into the dough.