It almost goes without saying that you need to insure against loss of money or theft, if you are taking large sums of money about with you. There are also schemes for registering and insuring keys and credit cards - if they go missing only one email to the relevant organization is necessary; they will do everything needed to safeguard you from the effects of misuse.
If you are not in such a scheme, always carry with you a note of your card numbers and the email address and telephone numbers of the issuers so that you can report any loss at once. Most insurers will only undertake to protect you, from misuse of your cards if you notify them of their loss within a stated period. Make sure you know what this period is so that you don't do too little, too late.
You should also consider covering yourself against the cost of medical treatment abroad, which can be alarmingly expensive, and also against the cost of returning home in case you cannot do that in the way you intended. Car repatriation can also be covered.
There are many schemes available for these.