There is only one rule when talking about job, or essentially anything in life, if you wan to win. And that is - always be ready to walk out. This mostly means able, not just willing. Never put yourself in a position where you are cornered and have no way out. This is where "fuck you money" comes in, usually. If you know you will have food on the table, roof above your head and a bed to sleep in, your perspective will be quite different than a person that is one blown up tyre away from getting evicted.

And secondly, when it comes to jobs, always look for a job while employed. And not just that, you can use that to renegotiate your salary and benefits with your current employer because hiring new person would also mean mentoring them in the company culture and know-how and things like that, that you already know. So it is a cost to them that might be, and usually is, much higher than increasing your salary.

And a tip for the road, make sure your pay increases every year, either with inflation or based on agreed upon percentage(like 5% a year, for example). Inflation is universal and companies increase their prices accordingly, yet workers never require increase of their salaries, usually until years later.