Y'all are just lazy, get some backbone…
Seriously, I'm at the “end stage” of my work career, most of which has been as an IT or infrastructure contractor but I've also done a LOT of other random work during those occasional periods when the good contracts were scarce and here is what I've learned from that.
1) Jobs come and go. Sometimes they go because of something YOU did. In that case “learn and do better” and then move on. Mostly jobs go away because of something completely out of your control regardless of the blame assigned by whomever is doing the firing. When that is the case, walk away and take some time to recover and then move on.
2) A “support network” is an absolute necessity. Maybe it's family, maybe friends, maybe a church, or a mix of all that and more, but no matter what happens or how bad you feel don't cut off your support network because you'll need it and because the most surprising opportunities can arise from the most random interactions.
3) Be specific and GET IT IN WRITING! What the “tell you” what they “promise you” what they hint at… NONE of it matters at all. The only thing that matters is what you get in writing for later reference. If a job “promises” you a raise but won't put any specifics in writing then there IS NO RAISE! If they want you to take on a “few additional duties” but won't specify the details in writing then what they really plan to do is dump as much on you as they can possibly get away with. If they play the “offended” card you tell them “I'm sorry you feel that way but I would still like this in writing”. If you get fired over asking for things in writing then your job was about to go away anyway. BELIEVE ME on this one!
4) Cover Your Ass! Keep a daily work-log. It doesn't need to be fancy but it does need to list your tasks for that day. When you get “called in” over an issue and asked what you've been doing it really makes them squirm if you haul out a notebook and start giving them day-by-day lists of the tasks you've been performing.
5) Food, Clothing, Shelter and Medical care. THESE are the reasons you are working. Not for “exposure”, not for “experience”, not to “be part of the team” or to “help out” the boss. REMEMBER WHY YOU ARE WORKING and if a job tries to dismiss that as though you are being somehow petty (Oh you're 'only here for the paycheck') set them straight. Work should be an even transaction and if your work isn't fully satisfying the needs listed at the start then you aren't actually an employee, you are a paid volunteer.
6) Give it a week. Short of actual physical threats or abuse or danger, give any situation you encounter at least 24 hours, preferably a week, to shake out. MANY things in professional environments are ultimately misunderstandings or simple incompetence and it is hard to make good decisions in the heat of the moment. However, any actual threats should be resolved by physically leaving, immediately.
7) Discuss your pay with your co-workers (off site, outside company time). This is a protected right and all workers need to make sure that employers are treating everyone fairly. Document the conversations in the work-log mentioned in #4.