Here is the hat I've knitted to go with the yoda jacket I've knitted for Poppy.
It's aran weight yarn on 5mm needles.
I started with 50 stitches and did 6 rows of moss stitch, then stocking stitch until it was about 14cm long.
Then I decreased by knitting 2 together every few stitches - can't remember exactly, but I decreased on each knit row for a few rows until there were 9 stitches left. Then I threaded the yarn through those stitches and pulled it up tight before tying. It was crying out for a fluffy, floppy bobble.
This is a Christmas present, but I was worried it wouldn't fit, so I just let Poppy try it on for size.
I still have loads of wool left, so I've started a scarf now!