Trust your instincts. Don't tolerate awful people. And if you don't have time to do something, don't commit to it.
Ms. Write's Guide To Life, Lesson Two
If choosing between projects, always go with the one that has previously paid. While we all cross our fingers that contracts or handshakes mean something, it's not until you have a check in hand (and deposited in the bank!) that we know we can trust an editor.