I don't know if this list is complete but as to my knowledge it is so thought I'd share it with anyone. Now that I have the DVDs of all the NCIS seasons as I go back and rewatch them I'll be able to keep the list updated and accurate.
Rule #1: Never let suspects stay together.
Rule #1: Never screw over your partner.
Rule #2: Always wear gloves at a crime scene.
Rule #3: Don't believe what you're told. Double check.
Rule #3: Never be unreachable.
Rule #4: The best way to keep a secret? Keep it to yourself. Second best? Tell one other person - if you must. There is no third best.
Rule #5: You don't waste good.
Rule #6: Never apologize. It's a sign of weakness.
Rule #7: Always be specific when you lie.
Rule #8: Never take anything for granted.
Rule #9: Never go anywhere without a knife.
Rule #10: Never get personally involved in a case.
Rule #11: When the job is done, walk away.
Rule #12: Never date a co-worker.
Rule #13: Never, ever involve a lawyer.
Rule #15: Always work as a team.
Rule #16: If someone thinks they have the upper hand, break it.
Rule #18: It's better to seek forgiveness than ask permission.
Rule #22: Never, ever bother Gibbs in interrogation.
Rule #23: Never mess with a Marine's coffee... if you want to live.
Rule #27: There are two ways to follow someone. First way, they never notice you. Second way, they only notice you.
Rule #35: Always watch the watchers.
Rule #36: If you feel like you are being played, you probably are.
Rule #38: Your case, your lead.
Rule #39: There is no such thing as coincidence.
Rule #40: If it seems someone is out to get you, they are.
Rule #42: Don't ever accept an apology from someone who just sucker punched you.
Rule #44: First things first, hide the women and children.
Rule #45: Clean up the mess that you make.
Rule #51: Sometimes - you're wrong.