Communication
Be honest
Don’t be shy

speak up

Cause their good listeners

To grow a pair and talk to them.

Body language

I don't know maybe just maybe prepare some questions to ask ahead of time, and surely eventually the right question will be asked which will get the girl talking more, and maybe eventually when she's talking she'll say something that helps the guy come out of his shell. I don't know if that made any sense, but that's all I could think of. Other times humor can help break the ice as well.

Date other introverts.

Closed mouths don’t get feed so if they are quiet they wouldn’t be able to connect with you.

I guess by their body language

Send pics lol