I would gather up as many weapons as i can (i have many weapons in my home, most of them are military grade and PLEASE don't ask how i got them) and tear down my apartment staircase (sounds dumb but zombies cant get up and i can get down with a ladder) and just....live.Occasionally i'll go scavenge a supermarket or something.As for defence....that's not so hard considering my closet is basically an armory.If i'm away from home when it happens i'll just go back home or join a survivor group.If it's near the end of the world i'll try to impregnate as many women as possible to restart civilization.