Wrap all your sensitive computer equipment in bubble wrap!
Like the Carrington Event.
Back in 1859, there were no satellites or delicate chip technologies to wring their hands in angst about. So what could a solar storm do? On September 1, as viewed and reported by Richard Carrington, it did a lot more than you might think. Telegraph offices across the world got whacked by the flare. Some telegraph operators even reported electric shocks and, in multiple cases, claim paper caught fire.
Now the NRC says that a similar solar storm could cause up to $2 trillion dollars in damage. In a best case scenario. Some scientists are giving better than even odds that a Carrington Event type of storm is going to occur. If it does, you better hope you're wearing rubber soles. And stay away from telegraph offices.