In both his book Rawles on Retreats and Relocation and in his survivalist novel, Patriots: A Novel of Survival in the Coming Collapse, Rawles describes in great detail retreat groups "upgrading" brick or other masonry houses with steel reinforced window shutters and doors, excavating anti-vehicular ditches, installing warded gate locks, constructing concertina wire obstacles and fougasses, and setting up listening post/observation posts (LP/OPs.) Rawles is a proponent of including a mantrap foyer at survival retreats, an architectural element that he calls a "crushroom".
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!