I doubt that it would be possible to survive a direct impact by a large comet.
Short term survival might be posible in an underground shelter, half way up a mountain, but what about afterwards ?
The destruction would include virtually all modern infrastructure, and with no hope of rebuilding with almost all the population dead. Even growing crops would be likely imposible owing to the clouds of dust/ash/smoke blocking sunlight.
Even a near miss would be as bad, tidal effects would result in waves MILES high that could wash away mountains, let alone man made structures.

That is the worst case though, a smaller impact might be surviable with some preps and a lot of luck.
The effects of a small meteor or comet strike would be a bit like the detonation of a large nuclear weapon.
Surviable near by ? no way ! but at a distance, yes surviable.

I cant think of many preps specific to a meteor strike, all the usuall preps of food, water, fuel, tools, and so on would help.
Food is arguably of greater importance since crop yields would be much reduced, perhaps for years.