Write your name on the board so that there are no questions about how to address you.
Prepare a five-minute introductory speech before you arrive in the classroom. Tell the kids your name, how long you will be there, how you expect to be treated and how you will treat them. Include information on the punishment for misbehavior. Explain that the fact that you are a substitute does not mean you will not call parents at the end of the day before you go home. End your speech with a pleasant note to get the class on the right track.
Bring educational crossword puzzles, math games and reading material for the students in case the teacher doesn't leave materials for you or you have students that finish work early. Explain that all work will be turned in to the regular teacher and may be graded.
Begin class by standing at the front of the room and wait for the classroom to settle down. Most students will begin to quiet down as they wait for you to begin speaking. If they do not quiet down, turn the lights off and on. If they continue to talk, pass out the assignment for the class period. Explain that you can help them complete the task or they can work on their own. Either way, the assignment must be turned in at the end of the period. Explain that you will need the full attention of any student who desires to receive help.
Take 10 minutes of classroom time to let the students stand and introduce themselves to you. Write down their names and explain that you will be using the names to take roll. While this may seem like a waste of time, many substitute teachers will waste entire class periods just trying to get the students' attention. This 10-minute exercise will let the class know you are in charge and will set the stage for getting quality work completed.