The most important-but-forgotten salary negotiation tip is: finish well. In sports they call it the follow-through. When it’s over, be happy.
So you wanted more, and you pushed for it, which made you nervous when you did it, but they gave you more than they originally offered, although it was also less than what you’d hoped for. And at this moment you know that this is what you’re getting. Further pushing isn’t going to work.
Scene one: you shake your head, look down, grimace a bit, sigh, and say something related to how that’s the best offer, but you’re still disappointed. You walk away leaving your boss wishing he or she hadn’t given you that extra bit.
Scene two: you look them straight in the eye and thank them for the extra push. You show relief. You mention how you hate salary negotiations with people you like, and you’re glad that’s over. You tell them how much you like the job and the company. You leave your boss glad he or she added the extra.
Either way, you got what you were going to get. Even if you are disappointed, and looking for another job, or deciding to start the new business, keep that to yourself. In the meantime, whatever it is that you’re doing in the current job, do it well. The people you deal with as you go through jobs will remain with you, as friends and references, for a long time … or not.