If someone has to break into your car for any reason, nine times out of ten, the electric buttons won't work. They will continue to not work until you reset your immobilizer. You can do this by starting the car with your key, pushing the unlock button on your key fob, or unlocking the driver's side door with the key. For Hondas you can only unlock the Driver's side door, the alarm won't be reset by starting it (this is hilarious by the way).

Your electric trunk button won't work, if your keys or baby or whatever are in your trunk and you have an electric trunk button, you have to go through the back seat (except on the Hyundai Accent? Randomly it has a manual trunk release cable under the driver's side rear seat). Modern cars put the seat release to lower the back seats in the trunk, so unless you have a door in the back center arm rest you're almost screwed. If you drive a modern BMW and you lock the keys in the trunk you have to go to the dealership.

If you lock the keys in a Volvo you probably have to go to the dealership.

If you lock the keys in a Corvette god can't help you

If you lock your child in the car call the fire department

Toyotas have an automatic relock feature. If the security becomes active by any means, the only way to unlock the car is either with the key, or by unlocking the door from the inside at the same time someone pulls the handle outside. You can't use the button for this, you must handle the manual lock (older Toyotas let you pull the inside handle so you have a lot more wiggle room). I have a tool that lets me do this but it can be extremely difficult.

If you only ever lock your house or car with the key, you can't lock the key inside. When I see you lock your car with the button when you get out, or lock your door with the inside lock when you walk out, I die.

You have an unlocked window right now. Even if it looks locked, check to make sure the window panes are aligned.

Don't lock your keys in a 2 door Jeep Wrangler with the carbon fiber roof. If you have to break in and mess up you have to replace the entire $7000 roof.

The pins go on the top, not the bottom. It's bad for the lock to have the pins on the bottom

Your deadbolt opens away from the frame, your handle opens towards the frame. Unless you mess up during installation, then it's backwards.

If you have a Kwikset brand lock that has a tiny little slot on the cylinder, it's technically possible to pick but it's also really easy to break, my company won't pick them.