Use the following trick to avoid breaking bobby pins when trying to pick a lock. Just before the bobby pin is going to break, exit that screen then go back. You will save a lot of bobby pins by doing this. This also works when trying to get a password for computers.

To always pick a lock successfully, go to the door, safe, etc. and save the game. Then, start the sequence and choose "Force lock". If you fail, just reload and try again until you do it successfully. This requires only one bobby pin.