Cookies (what I've learned)

Measure exactly.  Use unsalted butter.  Sift the flour with whatever the recipe calls for.  Whip the sugar and butter for no less than 10 minutes - creamy needs time.  When it all comes together you're only 1/3 of the way there.  You've got to cool the dough for a while; a long, long while.  The colder the better.  When it comes time to cook, use the top rack with another empty pan underneath.  Watch the first batch closely, times vary from batch to batch, but usually not within the same batch.  Enjoy cookies all the time - making them, eating them, and sharing them.