Make two copies of your passport, driver's license, airline tickets, and credit cards. Pack one in a safe place in your luggage and leave the other with family or friends. Your family also needs a copy of your itinerary, complete with hotel contact numbers, so you can be reached in case of an emergency at home.
Your list of traveler's check serial numbers is important. Leave one copy with your family and pack the other list where you can access it easily. Every time you cash a traveler's check, cross its serial number off the list. If any of the remaining checks are lost or stolen, you'll know exactly which serial numbers belong to the missing checks.