I am going to use them for marking my rounds when doing amigurumi if that helps! I heard you can use them for putting your finished pieces together to line them up for propper placement before sewing legs and arms on
I use small safety pins, either the tiny gold ones, or the silver that are a bit bigger.
I use corsage straight pins or even other thin crochet hooks to hold ami pieces together as joined.
Check out June Gilbank's site PlanetJune. The best tutorials for everything amigurumi!!!
Also get one of June's little tools to help stuff the little arms and legs of your creations.
Sounds like you're on your way!
I use bobby pins! They work wonders and they're cheap. They're easy to slide on and off with one hand, but they don't fall out. I always use them for Amigurumi. Plus, they're always laying around anyway.