Inapproporiate behavior on school grounds before and after school

You know what inappropriate behavior looks like - what are some examples from your experiences?
Here's is the solution to the situation:
1) Have rules posted throughout the school
2) If at all possible separate the student from peers during school
3) Make sure that the student does not have any down time while on school - encourage participation in school activities to decrease the likely hook of free time - which usually equals trouble causing.
4) Give the student a responsibility in the building
5) Teach the kid to "think" before acting.