Here is a site with basic info. Much of this has been around since the 1950s: https://www.ready.gov/nuclear-explosion

A lot is going to be dumb luck, since you can't necessarily determine your distance from a misdirected or erratic missile. Get upwind and under cover.the more the better.

Going abroad might help, but since wind and water currents don't respect political boundaries, bad things will circulate across most of the planet..

There is talk of manned exploration of Mars by 2030. Any takers?