In my experience as a recruiter, negotiating with both men and women, the men do seem to be more aggressive. Of course, this isn't scientific; it's just what I recall.
In my own personal salary negotiating experiences, I've had another person that I could talk to and compare notes about what I should do. Early in my career, it was my dad and he gave me good advice which I took. But this was after I learned a lesson.
My first office-type office job out of college, which I took on during that horrible recession when I was really worried about paying rent, I recall the company head (it was a small commercial real estate company moving toward REIT status) asking me how much I needed to make to "get by". Stupidly, I told him and that is what he paid me. I was a kid. I had no idea what I wanted to do with my life and I really needed this job. I worked there for 2 years and my disappointment in myself and my lack of respect for the person who wanted to pay me the minimum amount possible (no raises...surpise!) both grew. At the end, there was a big project that they were going to hire a temp to do. I offered to do it on evenings and weekends if they would pay me what they would have paid the temp for the time. it actually saved them money because there was no agency fee. I worked some crazy hours and got a nice chunk of money (at least at that time), which I used to quit my job and move back to Chicago. And that is the decision that led me into recruiting.
By the time I was negotiating my next job (about 6 weeks later in Chicago), I made sure that I was ready to play. I had been working as a temp so they knew what I was making and that the amount wasn't what I expected to be making as a full-time employee. So there really wasn't a lot of context or precedent to use to justify any particular dollar amount other than what I would accept and their internal equity. So when they asked me to tell them what I'd need to take the job, while I was still worried about paying rent (on my little studio apartment), I knew not to make the same mistakes I had made the last time. "What were you thinking of offering?" was my response, heart pumping. Their number was higher than the secret number in my head (plus there's HUGE upside in the agency space so there was plenty of opportunity to make more, which I was very excited about). I remember thinking: "Holy cow! That worked (thanks Dad)!"
By the time I was well into my recruiting career, I was a pro at negotiating. I've interviewed and parted ways with a couple companies that couldn't or wouldn't meet my salary demands. But that was OK. What was important was I had salary demands. I knew what I was worth in the marketplace and I wasn't taking less. And I found other companies that I wanted to work in that made me the right offers. I've always kind of appreciated the companies that will have a "ballpark" discussion with you at the beginning of the process so you don't take the time interviewing for a job that you would never acccept due to the compensation. Trust me, recruiters don't want your reaction to their job offer to be disappointment.
Now, I still have an aversion to talking about my money, especially about splitting up checks at lunch. I'd rather be the person that pays a few dollars more than do the "but you asked for extra cheese so you owe more than me" thing. But when it comes to negotiating salary for myself, I force myself to get over it and just do it. I never really thought about it as "negotiating like a man", just being a better negotiator (which isn't necessarily the same thing as just being a more aggressive negotiator because you need to know when to back off too).