Well assuming an explosion, and that we get sulfur dioxide into the atmosphere...that would create slight temperature drops.
Famine would be an issue

Its the ash that's the biggest problem, veggies and plants would mostly die.
Since new vegetation would start to grow in about 10 years, you either migrate south into central and south America or hope for a major cleanup.

The ash is sharp as well so it would clog many cars, electronics and not good for you to breath in

So I would say have a very good green house or 5 ready, stock up on seeds and backup power...solor would have issues..so maybe.wind? geo thermal?
Do what you normally do as a prepper. Stock up and be ready to grow things under a greenhouse.

SOme basic suggestions.

things to consider is how long would the ash be in the atmosphere? Could you clean up enough after the initial fall to keep going? What about livestock?