Knowing what you have now can save headaches down the road.

Close your eyes and make a mental list of the things in your home. Television, furniture, clothes, computer equipment, and more.

Now, close your eyes again and imagine this scenario. You’ve just come home to the scene of a burglary, and not only do you need to make that mental inventory, you need to recall the price you paid for the computer equipment, the store where you bought the furniture, the value of the clothes, the exact model of the TV. Stressed yet?

Happily, you can prevent the mad scramble to recall all that by making a personal property inventory now. A complete inventory will help the police identify your property if it’s found (more on how, exactly, later); help you get reimbursed through your insurance policy (and determine whether you have enough coverage); and help you sleep better at night.

Here’s how to do it.

Go room-by room

Pick a room and make a list of everything that’s in it. Use a computer spreadsheet or simply write it on a piece of paper. Each entry should include a description of the item, how many you have, the date you purchased it, where you purchased it, the original purchase price, and the current estimated value (i.e., what you could sell if for). When it’s relevant, record model and serial numbers. Once you’re done with the list, do a walk-through with a video camera, identifying all your stuff. Alternately, take pictures —detailed pictures including those serial numbers—and attach the pictures to each room’s list.

While you’re doing your walk-through, consider marking valuables according to the directions of Operation I.D., a program recognized by law enforcement for 30 years. Operation ID suggests engraving or indelibly marking valuables with an identifying mark (not your Social Security number), such as your driver’s license with the state abbreviation followed by the number (e.g., CA-B1234567). Keep in mind , of course, if you move out of state that your license will change.

Collect your receipts

You may not be in the habit of keeping receipts, but here’s a new reason to start: insurance companies expect a proof of purchase for big-ticket items like electronics, furniture, jewelry, and tools. Even receipts for kitchen appliances and smaller items are helpful. For organizational purposes, consider filing these receipts with the room they correspond with. And, as the NAIC reminds: include in your inventory the things you don’t use very often—or that might be in storage—like holiday decorations, sports equipment, or tools.

Get your things appraised

Naturally, you won’t have receipts for some things, like the emerald earrings you inherited from your grandmother, or a painting with no provenance that’s been in the family for generations. An appraisal may not give you the price you feel your collectibles are worth—but it will give you proof of fair market value. Items to consider getting appraised include jewelry, antiques, artwork, rare coins, silver and gold, and other collectibles.

Secure your inventory

Your inventory won’t do much good if it’s in the same house that gets ransacked, fire-damaged, or flooded. Store a copy in a safe deposit box and with your insurance company, and keep digital pictures on a digital storage device or in email.