Which Is Your Prime Hand in Sign Language?

Yeah, the other posters are right. Usually it's called the "dominant" and "subordinate" hand, but it's basically the hand you're most comfortable with.

I'm right-handed, so that's my dominant hand when I'm signing. If only one hand moves during a sign, that's the one that moves. That's the one I use to fingerspell or produce one-handed signs.

If I was a lefty, everything would be reversed.