If possible, make sure each small group has both genders. Mixing genders is important because youth may have trouble practicing with the same sex if scenarios involve saying no to or communicating about sexual situations. Use sets of instructional cards for each small group to help keep them on task. Use props to help youth get into the role plays. For example, clothing, an old couch, chairs facing back to back if it is a phone conversation etc.
Props also make the role play fun.
Have the instructions for the small group practice written on the blackboard or newsprint so the small groups can refer to them if they get stuck. Decide on a method to indicate when youth should switch roles during the practice. For example, you could ring a bell, flick the lights, appoint a time keeper in each group, etc. If you are doing practice in one large group, have youth who aren't role playing act as observers. Be sure that everyone gets a chance to practice the skill.