The first step is making a list of your possessions, including descriptions, purchase dates and any receipts of appraisals. For clothing, count the items you own by category and note any especially pricy items. For major appliances and electronic equipment, attach any sales receipts and include serial numbers (usually found on the back or bottom of the equipment).
Next, take a video. With smartphones being ubiquitous today, any one can take filmed inventory of their belongings. Make sure you get complete shots and close-ups on unique features. At the very least, take some still shots and upload to a computer file.
For possessions such as jewelry, art, rugs and tapestries, collectibles, etc., your standard homeowners insurance policy may not offer any coverage at all. Check with your insurance professional to see if additional coverage is needed.
Finally, do a complete walk-through of your home, including any additional buildings. Then take the inventory files on whatever medium you chose, and put it in an off-site secure place. For those so inclined, there are several computer programs, many free, that can assist with your home inventory.
Whether you are just beginning to set up housekeeping or have lived in your home for decades, it is impossible to recall every single thing you own. Add in the trauma of a household disaster like a flood or fire, and your memory gaps will become as wide as the Grand Canyon. Obviously some losses are irreplaceable. But for those that can be replaced, have the documentation necessary to get back everything you can.