I'm an NCIS fan.  And I have noticed that some of Gibbs' rules apply quite well to the classroom.

Rule 3:  Don't believe what you're told. Double check.

Always - no matter who told you.

Rule 5:  You don't waste good.

Your students are good.  Don't waste that.

Rule 8:  Never take anything for granted.

Rule 14:  Bend the line, don't break it.

Sometimes you have to in order to teach.

Rule 15:  Always work as a team.

Rule 18:  It's better to ask forgiveness than ask permission.

Rule 20:  Always look under.

For lost papers.  For the real reason they aren't working or are angry.

Rule 28:  If you need help, ask!

You and them

Rule 36:  If it feels like you're being played, you probably are.

You don't have to explain why you think you're being played.  You can just call them on it.  I took away bathroom privileges from a class because when two students returned to class, they made me suspicious and I couldn't tell you why.

Rule 39:  There is no such thing as coincidence.

Rule 45:  Clean up your messes.

Rule 51:  Sometimes - you're wrong

Apologize to students - in front of others, if possible.