In your first class, you are trying to do several things:
-develop a good class dynamic
-assess your students' level
-present course information and guidelines
One way of accomplishing the first two is to have students interview each other in pairs, and then present their partner to the class. Depending on their confidence/level, you could brainstorm a list of questions to ask during the interview. After the oral activity, you could have students write a biography of their partners, which gives you further info about their level/needs. (Always make it clear that students don't have to answer questions that they are not comfortable with).
As a warmer, I've often brought in pictures or items of mine that I thought would make students curious, and told them I would answer any questions if the questions were grammatically correct. Students then worked in groups to generate questions. Another possibility is to write the answers to some personal information questions on the board, and students work in groups to create the questions.
In introducing course outline/schedule/expectations etc. you could have students tell what they expect to learn in the course, what they think students need to do to succeed in the course, etc, and then you can go over your course info with them.
Oh- one thing I always tried to do with a new class is ensure that I knew everyone's name by the end of class, and that all the students were comfortable with most of the names by the end of class.
I hope this helps.
- For Teachers