Whether you’re an amateur or an experienced negotiator, you realize that most people are not going to make their first offer their last, at least not when you’re dealing with money. That makes it easier to go first and shoot high or low; you can always backtrack.
I’m not going to tell you that you can’t break that rule—there are certainly circumstances when you should, and if your personality is one shot and out, then go for it. But if you do intend on breaking it, make very clear, very very clear, that the figure is not going to be negotiated. Say, “This is my final number,” or words to that effect. Not, “I thought I’d pay this.”
Which brings us to a general rule about making demands: If it’s non-negotiable, say so when you bring it up. Save yourself the hassle of a long-drawn-out test; suffer only a shorter one instead.
But be very comfortable with your out, because you may have to take it.