1. Never Target a Scapegoat Who Can Fight Back
Christie ladled all the blame on his Deputy Chief of Staff, Bridget Kelly. To color the accusation he described her as an insecure slut incapable of rational thought. She's a bad choice. Kelly is an experience political operative who knows how to defend herself. At the beginning of the scandal Kelly was a loyal Christieite willing to take the hit for her boss, secure in the knowledge that her loyalty will be repaid in time. By scapegoating her, Christie has turned a loyal friend into a formidable enemy. A better scapegoat would have been some low-level civil engineer with drug problems who has recently died.
2. Don't Be an Arrogant SOB
3. Be an Ignorant Simpleton
Christie has tried an odd variation of this tactic. His position is that he was so focused on the grand issues, like the origins of the universe, that he couldn't be bothered with the minutia of day-to-day governance. He claims ignorance because the petty problems of the people of New Jersey are beneath him. It's an interesting tactic that I can't see working.
4. If All Else Fails, Tell the Truth
Chris Christie would rather wear a tutu in public than resort to that.