Save your money.
Stack up ammo, water, food, medicine and antibiotics, and warm clothes.
Hope for the best, although if you have no military training you might not survive long fighting a russian invasion, unless you team up with the canadian forces, which would consider you more a liability than anything... Maybe read a few books on guerilla warfare, there is a good one written by a german african officer during ww1.
Works great for: russian invasions, zombie apocalypse, yellowstone volcano eruptions, falling skies alien invasions, massive earthquakes, ice storms, sharnados, katrina huricanes, etc.
Doesnt work great for: surviving nuclear war, fighting tanks, fighting drones, fighting artillerie, etc.
Mike knows what he's talking about XD.
You can run and gun all you want, but even the most pimped out rifle and a stack of 5rd mags wouldn't protect you against 23mm cannon shells coming out a mile away from a gunship that spotted you on its FLIR and the pilot deems you a bit too suspicious for your own good. Modern warfare is more than about having a man on a gun trigger, that being said, the most valuable contribution a civilian can make during an invasion is intelligence gathering for his side. Information is what wins modern wars.
Mao's Communist forces didn't have numeric nor qualitative superiority over his Nationalist counterparts, but what he did have was a legion of sympathetic countryside peasants who fed him info and warnings on where and when Nationalist troops were moving, enabling him to evade his opponent and prevent his smaller forces from being pinned down. I don't know what he did after that, but his people are now sitting in Beijing, so he must had knew a thing or two about winning wars, if not economics.