Depends. Driving versus flying, domestic vs international...

Probably the most important prep is just enough money to either extend your stay or pay for an emergency flight back home if something goes wrong. Really, about the most versatile prep. I'd make sure you have enough in your bank account, but also have a good amount of cash in an inconspicuous and pickpocket-proof location (i.e., not your wallet / back pocket of your pants).

Beyond that, you can obviously take a lot of stuff with you when driving domestically. I actually have an entire small suitcase packed with "extended hotel stay" essentials, which include medical supplies, extra clothing, PPE, food, tools, etc. Also a smaller bag of car-related gear, including tow straps, spare fuses, tire and radiator repair kits, road flares, chains, shovel, and so on.

International air travel is about the worst possible scenario. If you have room, you can take some basics with you - some emergency rations, an empty collapsible water jug (that you can fill in when you arrive), a flashlight, maps, etc. But you probably won't have a lot of room, and there's plenty of prepper stuff that may get you harassed by the customs or by airport security - even a pocket knife may be an issue in some countries. I usually carry a satellite communicator (Garmin inReach) on hiking trips and when traveling somewhere far.