Electronically scan your travel documents and email them to yourself. If you don’t have a scanner, use the camera on a smartphone or similar. When I was young it was traditional to photocopy your passport and visas, travel insurance, etc, and keep them in a separate part of your luggage. But that’s now so old-fashioned.
Photo Gallery Scan All Your Major Documents on Your Vacation
Scan All Your Major Documents on Your Vacation Images
These days, digital is best — that way your documents won’t go missing even if your bags do. And you can have clear color images of your passport, ID card, visas, etc. to refer to or use to prove your ID if you lose them. And in the case of travel insurance, the insurer may well give you a copy of the policy in PDF format, also worth having on your smartphone, tablet, laptop, etc.
If you are using more than one computerized device then put copies of all these on all of them, but not where they are easy to find, in case someone steals one of them. You could put the files in a folder with a neutral name, e.g. Underwear, Carpet Suppliers, or something else just as ridiculous.
You can also keep copies online in a Dropbox account, Google Drive or something similar.