This is my standard worsted-weight recipe. I cast on 88 sts (or something like that) on a smaller needle, knit ribbing, switch to a bigger needle and knit until the hat is about 7". I hold it against my hand for this. If it reaches from the base of my palm just past my fingertips I'm ready to start decreasing. On 88 sts I do 8 decrease "wedges," so k9, k2tog around, etc.
I have a little of the green left so I started a new X-ing X's that will have a contrast color band. If you knit an X-ing X's please add it to Ravelry so I can see your hat!