-I used a glass vase for one of my hats as it works for my size. I do mostly baby stuff and my kid wouldn't sit still. lol. But it works well and holds it up higher than just a styrofoam ball.
https://www.etsy.com/listing/176450790/bunny-ear-crochet-hat-baby-toddler?ref=shop_home_active_5-I suggest looking at a shop you admire in your genre that does well. See how they write descriptions, tags, etc. Don't copy their stuff but just get a feel how a successful shop does their writings. I find it helpful.
-The tags for this hat:
https://www.etsy.com/listing/203613622/home-made-off-white-colored-slouch-hat?ref=shop_home_active_2I would never search for hat with the keywords "22in diameter." Your tags should be what a customer would search. Also, you want phrases not one word tags like "knitted" or "off-white." Knitted hat, teen white hat, off-white hat, etc are all a bit better in terms of tags.