Crocheted ballerinas in the shop

Have you seen these yet?
https://www.crazypatterns.net/de/items/362/haekelanleitung-gr-37-42-fuer-hausschuhe-ballerinas-no-59
I think they’re great!
Good thing I’ve already practiced making those decorative flowers.
Although these decorative flowers look a little different from the ones I practiced making.
But I’m sure it’ll work out.

I do have one more
question, though: how do you actually keep the shoes from slipping off or being too tight?
I guess you have to be really precise when making them?

What kind of yarn should you use so your feet don’t get too sweaty?
Sock yarn or cotton?