For ease of use, you could also hide a fuel pump switch inside the car that you have to press before going. It's an easy but effective solution for protecting your car and needs basic tools / wires.
Of course, the important thing is making sure the wiring is well done (proper wire gauge) and the switch is actually in a hidden spot.
I installed a reed switch just under my windshield to unlock the doors. Swiping a magnet is easier than keeping a key in my pocket.
Getting myself locked out is more of a concern than a stranger noticing the switch and finding a magnet.
I'll even mention it on the internet, if any of you want to steal my car, please just fill up the gas and return it after. Thanks.
Of course, the important thing is making sure the wiring is well done (proper wire gauge) and the switch is actually in a hidden spot.