These are a legendary set of rules developed by the American intelligence operators during the Cold War to be used when working in Moscow.  The list below is from the International Spy Museum in Washington, DC.

1. Assume nothing.
2. Never go against your gut.
3. Everyone is potentially under opposition control.
4. Don’t look back; you are never completely alone.
5. Go with the flow, blend in.
6. Vary your pattern and stay within your cover.
7. Lull them into a sense of complacency.
8. Don’t harass the opposition.
9. Pick the time and place for action.
10. Keep your options open
11. Once is an accident. Twice is coincidence. Three times is an enemy action.