Verify your oven temperature. Thermostats aren't always accurate. Buy a thermometer and hang it inside the oven. Set to 350°F and see where it really is. Adjust accordingly.
Baking is a science. Accurate measuring and using the correct ingredients is very important. Flour should be “fluffed” and then measured in a dry cup and leveled. Sugar and brown sugar should be leveled, too.
Never try to substitute baking powder for baking soda and vice-versa.
Baking powder and baking soda can become less potent as it gets older. That same old box you have spinning around in the Lazy Susan for seasons should be replaced with fresh. The same goes for spices.
Make sure butter, margarine and cream cheese are all used at room temperature. This will ensure that they blend with sugar smoothly.
The “fat” used in cookies makes a big difference. Butter results in crisp cookies. Margarine gives you soft and chewy cookies, but doesn't provide the unmatched flavor of butter. Usually a combination of the two will give the results you want.
Use parchment paper. No greasing needed and it makes clean up a snap.
When a recipe calls for chilling the dough, don't skip the step! Chilling drop cookie dough helps to keep them from spreading too much during baking. Chilling rolled dough makes it much easier to handle and means that you will need less flour when rolling.
Cookie sheets are the most important tool in cookie baking. Don't use dark sheets; they absorb extra heat and will burn the bottoms of the cookies. I prefer heavy shiny sheets and always have perfect cookies!
Always cool the sheets before putting more dough on them. Hot cookie sheets will cause the dough to start melting before you get them in the oven.
Try to make all the cookies on one cookie sheet as uniform in size as possible. Smaller cookies don't take as long to bake as bigger cookies.
Make cookie dough ahead of time, then set aside a different day for baking. It keeps the experience fun!
If you make slice-and-bake rolls of dough keep them on the short side and stand them up in a tall drinking glass in the refrigerator (this keeps them from getting a flat side).
When time is at a premium consider baking bar cookies. If you cut them smaller or in triangles they look great and are much easier (and faster) to make.
