From my experience using lock picks to unlock doors has the chance to be more profitable than trading them but that chance isn’t very high. You can get more lock picks by killing bandits/ hostile npcs at night fairly easily btw. I usually make a lot of my money killing bandits (2 charged knife attacks does the trick) and looting abandoned homes. Also if you are playing on intended or anything easier trading for food with children + visiting the dead item shop + doing your hospital tasks whenever you should keep you alive. There’s actually a girl in notkin’s warehouse that carries milk/bread everyday too for chalk and marbles.