Here is a little instructable for some hats I made a long time ago.
I made this from some left over fleece fabric. I recomend this fabric since it is warm and easy to work with.
Other warm fabrics are also good.
Step 1: Measure Your Head Circumference
Take a tape measure and put it around your head and measere the circumference of your head.
A nice variation on this is letting someone else measure your head.
Step 2: Choose the Hat and Addapt the Patterns to Your Head
Choose one of the patterns and use your measurements to addapt the drawings.
Or just use the ones on the ittle drawings, or just gues.
Step 3: Try Some Variations
Try some variations and break free