Shelter - prevailing winds, access to roads (good, bad, how far?), lines of fire (how far around are there no hiding spots for enemies? Minimum of 1/4 mile), easy getaway exit (tunnel preferred), neighbors (how far, what kind, do they accept outsiders, etc?), access to water, forget the backup generators (the noise will draw unwanted "guests"), weather patterns.
Is that enough for now on shelter?