One of the greatest mistakes a new teacher can make in a classroom (especially on the first day) is to assume that the student values the class as much as the teacher does. In a perfect world, that assumption would be true. In the "real world" of teaching, however, that just isn't the case.
As a new (or even a veteran) teacher, it is your responsibility to communicate to your students the importance of any class. In a sense, you have to sell them on the class. That is critical on the first day. If you don't convince your students that your class offers something of value that they need, then your dream class easily could turn into a class nightmare.
To validate that point, you don't have to look any further than your own experience as a student. How many times have you been in a class only to ask yourself after a week, "Why are we learning this stuff? How will I ever be able to use this in the real world? Who cares?" In fact, as you reflect on your own experience, you might still be asking those questions.
The point is, teaching is a process. You can't teach if students aren't listening. And students won't listen unless you first grab their attention. So, the question is, how do you grab a student's attention? Well, depending on what you teach, grabbing a student's attention could be either easy or a challenge.
Regardless, your job is simple: Remind your students where the pain is (as it relates to their personal experience), and show them how your class will help them relieve or avoid most of it. That's it.
For instance, I start every class I teach by asking a general question: "As students, what are you tired of?" I simply write every response on the board and relate a class objective (verbally) to one of their issues. Of course, no one class will solve all their problems, but they're quite impressed that it can solve or address any of them. Just be thankful you don't have to convince your students of the practical use of the quadratic equation (I'm sorry, math teachers).
Do you think you can show students how learning reading, writing, math, science -- whatever skills you teach -- can help them achieve some of their goals and relieve some of their stress (even if it's just getting their parents off their backs)? Hey, it's worth a shot.