Get to know your neighbors. Find out who you can trust, who you should defend, and who are your enemies. Remember that at least half of all people will sit on the fence and cheer whomever seems to be winning at the time.
Prepare the moral fortitude to do what will eventually become necessary. As Heinlein said, "When the need arises - and it does - you must be able to shoot your own dog. Don't farm it out — that doesn't make it nicer, it makes it worse."