Since there's no thread about this, and @Enami got interested in it, introducing:
"How do you play it?"
You simply click the cookie, until you sweat a lot, die, or your mom called. Whichever comes first.
Buy, upgrade and expand - it will help you. A LOT
If you do those three, they will do the clicking for you. And, your clicks will be twice as effective. How cool is that?!
Lastly, if you close the browser, it will reset. Save your progress by clicking Menu > Export Save (if you want a backup) then paste that somewhere; Menu > Import Save (if you want to play with your progress intact)
Post your progress and questions right here. Oh, and wrist pains. Have Fun~
Also, @Kirn has a link down there, but this time, it's meth.