Instead of explaining rules to students, I like to show them what the rule looks like and have students tell me whether or not certain behaviors are appropriate or not.
One year before school began, there were a few student government students who were wandering the halls offering to help teachers. I had them model different classroom activities. Here are three of the photos:
The first day of class, instead of just telling students about class rules, I asked them whether certain behaviors were "¿Apropiado o inapropiado?" (Appropriate or Inappropriate?). Students were interested because they knew the students in the photos. Also, students were the ones who told me whether or not a given activity was appropriate or not in Spanish class, and they learned two words without me ever having to give them a translation. There were even a few times throughout the year when students would yell "inapropiado" at another student (some of my favorite moments).