If you find a new job, ask for a 1-2 week vacation, that way if the new job doesn’t work out, you just come back. If you like the new job, just never come back to the old one.
When quitting, the reason you always give is “I can’t afford to work here anymore”. That way it’s clear that this is about money. If they want to beg for you to stay for a few weeks, ask them for a raise effective immediately, make it an amount that’s too good for you to refuse.
Never let their problems become yours. They are NOT your family. If they say you have to come in on your day off because Bob didn’t shop up, sounds like their problem. If you ask for a raise and threaten to walk out, don’t let them tell you that “yeah give me a couple of weeks”. No, you need the raise now or you are walking.
Don’t do work that you aren’t paid to do. If you are a janitor sweeping floors and you hear the phone ringing off the hook, don’t answer it. If you answer it, guess what, you are the new receptionist too.
Lastly, DO NOT use your personal phone for work or answer work stuff after you clock out.
Obviously this doesn’t apply to every single person, especially if you are outside of the USA, you don’t have to tell me that.