My easy pattern uses 2 skeins of medium weight cotton yarn held together.
Crochet Hook Size J

Instructions are for 7 sizes:
Small: 3 x 4.5 inches
Medium: 5 x 7 inches
Large: 6 x 8 inches
4 Extra Large: 7 x 9, 7.5 x 10, 8 x 10.5, and 8.5 x 11.