I always carry at least one spare door or main key on me at all time, when they were non-chipped keys I just carried a spare set on a tiny ring that let them lay flat in the pocket, or on the ring with my main keys. I never have other keys on my ignition key, its often not good for the ignition lock to have keys hanging from it, and if the truck was ever jacked/stolen I have no intention of letting them have a key to anything else I own, which includes the locking gas cap in older vehicles. I also never left registration or insurance info in the vehicle, always in my wallet on me. Not making it easy on them if they get stopped. No insurance or registration and they arent as likely to talk their way out of it. If you dont want to carry your spare chipped key on you, you can leave it with something youll never be far from or leave unattended, like your pistol or spare ammo. You can get chipped keys copied in a non-chipped form, they will open the door (at least on my 05 4runner) and can run accessories to close windows etc, but it wont start the vehicle. For a couple bucks a copy, its pretty cheap. I remove the plastic covering on non-chipped keys most of the time, it allows them to lay flatter in the pocket so they arent as much of a nuisance to carry. A sharp wood chisel works well to remove the plastic on the heads.
I keep the door remote in my vest pocket, or pants watch pocket or on a cord around my neck under my shirt, it makes it easier to get in the vehicle without fishing around in my pocket when attached to the ignition key, and gives another layer of lockout protection. I can hit the door unlock without getting it out, just by feel through the pocket or clothes.
Ive zip tied and magnetic boxed keys to the vehicle, and they came in handy a time or two, but I also realized all the minimum wage oil change guys knew they were there.
Ive locked myselef out enough times in bad places that I finally settled on the simplest and cheapest possible way to ensure it didnt happen again, always have spare keys on you at all times. Works well and is cheap.
Regarding basic security, never ever leave the keys in your vehicle when getting gas, (or "just going in the store for a minute..." Utter foolishness) and never leave the doors unlocked. Its a common way to steal cars, people basically giving them away for free by leaving keys in them. Another trick is sneaking up on the opposite side when fueling and opening the door and reaching in to take whatever they find and closing the door and walking away, most people never realize anything is gone until some time later, or at least until they are gone. Mine is locked anytime i cant see it, which includes standing next to it if Im not paying attention to it. In camp, in my driveway at my cabin way out of town, its never unlocked when Im not in it.
Some smart people never park near the door of a quick mart, or they park at the pumps even when not getting gas. If theres a robbery or trouble, you dont want to have to be right by the door to be able to leave.