Negotiations and self esteem

so a sort of offer was made today for employment. Salary negotiations have commenced. I've never really negotiated before. Mostly just took what was offered with a grateful heart because I couldn't afford to walk away.

Being in my unique position of having a choice means that I can make an informed decision. It also opens up the option of being too cocky and arrogant with an overly inflated sense of worth.

I've never been driven by pay. Yes, it's necessary and yes I like a bit o the green in my bank account but I have other requirements too. Will I like what I'm doing? What is the degree of difficulty?
Will I like who I work with?
It's especially difficult when you move around in the same industry. I don't want to be that person who says, "well when I worked at xyz company...." but at the same time experience has to count for something, right?

Oh, the drama.
It will be a nice birthday present methinks.