My trick is i focus on the people in the class i know. This is a new trick cuz i used to be very antisocial and wouldn't talk to anyone. If you're like how i was, then this won't help you much, sorry. But if you know people focus on them. It's like you're just talking to them in a group, like you do outside of class. And the other people are their friends who you just haven't been introduced to yet, but it doesn't matter, cuz you'll be introduced later. If you can get into that mindset, that helps. Also, at least 95% of those people are very sympathetic to the fact that you're nervous. You can do it!