I'm sure they are on the threads somewhere, but evidently they've gotten buried and people are asking. Plus, I don't think anyone's posted Tabby's.
As of the end of Season Four:

1. Never screw over your partner. (ie: betray) TONY: I don't sit on the sidelines when my people are in trouble.
3. Never be unreachable.
4. The best way to keep a screret: Keep it to yourself; 2nd best, tell one other personif you must. Thereisno third best.
7. Always be specific when you lie.
8. Never take anything for granted.
9. Never go anywhere without your knife. (BTW: Not sure about knives, but Abbysays she never leaves home without her hand-cuffs. ABBY's Rule #9 is "Always keep a spare, esp.Caf-Pow."
12. Never date a co-worker.
15. Always work as a team.
18. It's better to ask Forgiveness,than beg Permission.
22. Never, ever, disturb Gibbs in interrogation.
23. Never mess with a Marine'scoffee if you want to live.

Not numbered, but stated:
Never underestimate your opponent.
I don't believe in Coincidence. I do believe in bad luck. (The head in the car trunk.)
Never Apologize:It's a sign of weakness. Except between friends.
No such thing as an open-and-shut case: only water-tight.

FYI: The Paris, FranceNCISteam had a special rule: What Gibbs doesn't know, won't hurt us.