Here is my simple rules for a safe house;
1) Have the AO around the safe house mapped out.
2) Have LP/OPs observing all ways into the safe house.
3) Have a scanner, computer news, & radio to keep up on intell.
4) All "refugees" are under a "hostage taker" story to protect the safe house. "They took me hostage I had to help they had my family."
5) No outside contact...
6) One way in & two ways out, have an unexpected escape route (escape tunnel for example).

Include "dirty maps" with false safe houses and camp sites/cache points marked. Personally I think, abandoned buildings with a small caches of food, water & medical supplies would be better "safe locations" then actually manned safe hoouses.