I love making really fluffy pompoms – my strategy is to wrap the yarn around the rings until I can’t get anymore yarn on them. I usually use a 3.35 inch (9 cm) pompom maker.
Then, my favorite pompom making tip, use a fairly long length of yarn (I use 4-5 ft) to secure the pompom. I then trim the ends to an equal length and use a crochet hook to make a chain. Voila! Now I can secure the pompom but can easily remove it to wear the hat on the reverse side or when I need to clean the hat.
A tip from a wonderful reader: use a button inside the hat and pull the lengths of yarn through the buttonholes. This helps to prevent the pompom from pulling away from your hat!