I’ve lived in California nearly all my life, and I’ve never purchased an earthquake survival kit, nor have I done much else to prepare for the Big One. My lack of preparedness isn’t unusual; one recent survey found that only 40 percent of my fellow Golden Staters have a family emergency plan. When the massive quake hit Christchurch, New Zealand, last month my wife and I resolved, once more, to finally start preparing for the inevitable. We still haven’t gotten around to it.

Friday’s earthquake in Japan, though, has stiffened my spine. I’m preparing for a quake, and I’m doing it now. I’ve spent the morning looking for the best resources to get ready for disaster. Here’s what I found.

Buy an all-in-one kit. Getting all your gear in a single package may be more expensive than spending a day at Costco and a hardware store to assemble your own. The advantage is that it requires just a couple clicks, and you can do it right this instant (which is what you should do). You can find several kits at Amazon or the Red Cross . At $42, the Quakehold! Grab-n-Go Emergency Kit appears to be the best value. It’s got enough supplies—food bars, water, emergency blankets, first aid supplies, etc.—to sustain two people over three days.

Get extra water and food. From what I gather, you should treat these all-in-one kits as a starting point. Depending on your family and your needs, you’ll want to add extra supplies. For instance, many of these kits don’t include nearly enough water. An adult needs 1 gallon of water a day. (Older people, nursing mothers, and those in hot climates need more.) Since your plan should cover three days of potential outages, it’s a good idea to get loads of H 2 O. Bottled water is often stamped with a sell-by date, but these dates are mainly for stock-keeping purposes. Unopened bottles of water have an indefinite shelf life , the FDA says; water stored for long periods may taste a bit off, but it’s safe to consume.

You should also have enough food to last for three days. You can buy freeze-dried meals or food bars, but these can be expensive. It’s much cheaper to stick to canned food—just don’t forget the can opener!

Flashlights. Since flashlights, like pens and umbrellas, have a tendency to get lost, buy several; the Red Cross recommends that you keep a flashlight and a pair of sturdy shoes by each person’s bedside. Fortunately, LED flashlights are small and cheap (this Neiko Super-Bright sells for $4 on Amazon).

Radios. Most survival guides recommend that you keep a portable radio on hand to keep abreast of the news and emergency updates, but many all-in-one kits don’t include this crucial device. One of the most popular is the Etón Microlink , which sells for $30, and runs on solar and hand-crank power—you can turn the crank to power the radio and a built-in flashlight, as well as to charge your phone (the USB port will plug into most phones).

Other cell phone chargers. If you live in a sunny place and have a lot of gadgets you want to keep charged up, consider a solar charger. You put this $30 solar charger in the sun to keep its internal battery charged; plug in your phone, iPod, or other USB device for a quick backup charge. It’s also a good idea to get an in-car charger; they sell for as little as $4 .

Keep multiple emergency kits. You should keep your emergency supplies in a dedicated place in your house. FEMA recommends that you make your supplies portable; pack all your gear into a backpack so that you can escape with it in a hurry. But because you may not be home when disaster strikes—or your kit may not be accessible even if you are at home—it’s a good idea to keep extra supplies in your car and at work. At the very least, keep a stash of bottled water in your trunk.

Back up your data. If you’ve stored many of your most precious things digitally, it’s a good idea to back that stuff up when you’re planning for a disaster. This way you won’t have to scramble to save your photos, music, financial documents, and other things when you’ve got to leave. I recommend a two-step backup process : Save your data to an external hard drive, and also back everything up using an online service like Mozy or Carbonite, which will keep your stuff safe even if your hardware is destroyed.

Come up with a survival plan. It’s not enough to get supplies. You also need to coordinate with your family. This Red Cross page goes over everything you should discuss—the most important thing is to choose two locations where you should converge to meet one another.