Here's what I learned and the advice I would give.
-verbal promises are worth less than the air that the words are carried on. I stuck around working in a position I hated because I was promised a future promotion. It never materialized and likely never would have.
-it's nearly always easier to get a job offer from another company for $10k more than to get a $10k raise.
-ask up front what the interview process looks like. It's rarely worth your time to pursue a company with 4+ rounds of interviews. For me, none of those actually went anywhere because they had decision paralysis. Their lack of respect for a candidate's time is also a likely a red flag for how they treat employees.
-aim high with what you ask for. I asked for a pretty substantial 25% over the initial salary range (which was already a big bump from my former salary) and they gave it to me. Worst they can say is no.
-ask the interviewer what challenges they face in their own role. If you can propose yourself in a way that will solve those problems, you have a much better shot at getting hired and more negotiating room.
-learn to talk about yourself in a way that sounds really impressive.