I did my masters and current working on my PhD. I kept introduction short lol. It also helps to understand that if you're doing this in w class with more than, say, ten people, almost no one is going to be paying attention to you except the people that already know you and the professor. If you're doing research and have to present your work or doing a conference, you're the expert in the position (and also most people won't be actually paying attention). For me, treating things as if you're just talking with friends, very very informal, makes a huge difference.