Just practice bugging out. Call it a camping trip if you have family. Learn mountain man skills. If you can hunt, fish and trap, you will always have some meat. Buy a piece of land in the mountains, that nobody really wants and build a small bunker on it. Or find a place with a mine shaft that goes horizontal. Living in a hole in the ground would be horrible compared to a nice warm house. Better than dying in a nuked out metropolis I suppose. If they did it in the 1860's, so can you!