Everyone acts as if aliens don’t exist, but the reality is that we simply don’t know the reality. More to the point, there are billions of galaxies in the universe; it’s not hard to imagine that at least a few of them are home to alien life which is capable of travelling to Earth…and who might not treat us in a very positive way. No matter how beneficial aliens might be to humanity, we can’t just assume out of hand that their arrival will be a smooth transition. Therefore, should there be an alien invasion during our lifetimes, there are several precautions we, as citizens of Planet Earth, can take to keep ourselves—and our families—as safe as possible.
The first thing you can do is keep up with general survival techniques and ideas. Generally—and these are good tips for life overall, not just for disaster scenarios—you’ll want to know how to take care of yourself in case society collapses. For example, you’ll have to brush up on skills like wilderness survival (how to find edible plants, how to hunt, how to make a fire and build a shelter), self-defense and weapon handling (including creating makeshift weapons, using different kinds of weapons, and maintaining the weapons), and setting up your own home away from the grid (including how to find and use a water source, how to build houses and furniture, how to farm vegetables and fruits, and how to raise livestock). Furthermore, you’ll need to keep your accounts up to date; make sure that all your debts are paid off, that your securities portfolio is nice and diversified, and that you have an additional source of income.
Second, make sure you’ve stockpiled a lot of resources. In addition to food and water, you’ll also need a generator (for electricity), one (or several) first-aid kits, flashlights, batteries, and radios or walkie-talkies. Also consider having items that you can use for bartering; if aliens invade the Earth and society collapses, bartering will once again become a fundamental part of society. Goods suitable for bartering include duct tape, seeds for planting, fishing supplies, vinegar and baking soda (for cleaning supplies) and spray bottles. Also, if at some point you have to leave your house but know that you will return, lock up securely; you don’t want any aliens—or bandits—getting in there and stealing all your stuff/looting the place.
A further tip to keep in mind is that you can’t trust people, even if they’re your neighbors. If aliens do invade, you shouldn’t take for granted that they’ll look like little grey men. They might look like humans themselves, or they might have the ability to shape-shift so that they can take on our form, or to create holograms of ourselves.
Fourth, if you come into contact with the aliens yourself, act peacefully toward them. They might not want to create war; they might simply be exploring or looking for trading partners. By all means, use self-defense when it’s required, but don’t provoke the aliens unduly. They won’t appreciate it.
With all this being said, you’ll now be prepared for an alien invasion—or as prepared as you can be under the circumstances, given that we have no idea what aliens will look like or how they’ll appear to us. Best of luck preparing yourself; you’ll certainly need all the luck you can get!