Draw up a list of normative behaviors that you expect students to exhibit in the classroom. Include that list in your class syllabus and discuss it with the students on the first day of class.
Ask the students what other behaviors they would add to the list and include their ideas in your course planning.
Observe any students that exhibiting disruptive behaviors. The kinds of behaviors they exhibit and the things that they say may give you clues into why they are disruptive in class. Once you have an idea of what is causing the disruption, you may be able to do something about it.
Request that the student cease disruptive behavior. When doing so, remain calm and speak politely. Remind the student of the classroom rules that the classroom agreed upon on day one.
Request to meet with the student outside of class. Explain your concerns to the student and listen to the answers.
Expel the disruptive student from the classroom for the rest of that class period if the disruption continues. Do not immediately attempt to expel a student for an entire term; according to Kathleen McKinney of Illinois State University's teaching faculty, this kind of expulsion requires a due process for the student that should be explained in the school's community handbook.
Exhibit the behaviors that you wish to see in your students. If you requested, for example, that students not curse in class, then you should not, either -- no matter what any student says or does.