Traveling by vehicle is easy for preparedness. Assuming you have some space in the vehicle you can just bring whatever. Also your ability to control your own travel means you can choose to leave right now. You can go a hundred miles the wrong way to avoid a big problem.
Air travel is more difficult. Still I think you can be reasonably prepared for most even semi likely events if not the end of the world.
The most restrictive set of stuff for air travel is if you are only using a carry on. It is also what you can have on your person on the plane. What can you have? Listed in rough order:
-Good footwear. You don’t need hiking boots but shouldn’t be wearing flip flops or heals either. A decent set of close toed shoes you can walk a few miles in can fit with most styles and are very prudent.
-Decent all around clothes. Not combat or hunting gear but some kind of reasonable clothes in case you need to do something or get stuck in them for awhile. Also reasonable outer wear for your area.
-CASH. Probably the biggest single problem solver in real world survival situations.
-Credit Cards. Having a card with a big balance gives you options. Need a last minute ticket, OK. Heck if you need to buy a used car to drive out of a problem it is an option.
-Medications. Having a week or even better a month of medicines you need is very wise.
-OTC meds. Stuff for standard travel sickness like diarrhea, Tylenol, Benedryl, etc.
-First aid gear. Minus the needle I can’t see why you wouldn’t be able to have a full IFAK in a carry on bag.
-A water bottle.
-Maps. This is wonky as planes cover huge distances but even a state road map is better than nothing. Doubly so if you are not familiar with the area at all.
Now lets say you check a bag. For the sake of this a bag to anywhere. What can you add.
-A good knife.
-A multi tool.
Checking guns. Obviously on a flight to most foreign countries this is not an option. However when it comes to traveling in most of the US it is not a big deal to fly with guns. I have done it a few times and the only one where it got any scrutiny was in Louisiana at a local airport where the guy just wanted to see what I had. Really flying with a gun isn’t anywhere near as big a deal as people make it out to be.
That said if you travel to the same place often and can afford to do so it isn’t a bad idea to consider an operational cache.
How serious about all of this should you be? I suppose it depends. Primarily in my mind it depends on the risk level of where you are going. If I was flying into Northern Iraq or Pakistan or Indonesia would have things locked down. Thousands in cash a full on BOB, an as many weapons as you can get in and carry would be prudent. On the other hand if you were flying to a few hundred miles from home and it isn’t to a place with a high threat then some cash, decent clothes, a compass and a map an your not doing bad at all. Toss in a good folding knife and a gun or two and its a good set up for a relaxed area.