Keep a travel journal! I've been doing this for ten years now and you often need to go back and figure out where you were, when and why. It's insane. I have a

Keep a travel journal! I've been doing this for ten years now and you often need to go back and figure out where you were, when and why. It's insane. I have a physical book, that I periodically scan into my evernote. It's awesome, high quality paper and Its stood the test of time. Still not completely full. Arrival data, travel purpose, when you decide to become a "resident" of said country, when visa's/passport/PR card were renewed. After each trip, count the number of days abroad, and attach a note for travel purpose. Keep an index of those at the back.