Negotiation skills: job offer

I attended a negotiation skills workshop today and during the lecture, i realized how naive i was when i acceped the job offer.
"Negotiation" was the last thing that I had in my mind. Why? Because I was desperate to get A job. I did not know what "Base Salary" meant. I thought that was the walk away minimum level, not the salary before bonus and benefits. I didn't even research how much the average salary is for the position. Stupid!!!
I knew that I got the lower position because the director didn't see my academic experience as my real experience.
I researched a bit and realized that what I'm making is the far bottom (actually out of the average range when they applied my personal qualification/education level).

I know i should be very grateful to get the current job so that I can make a living and have a good life in a new city. But, it's important to market yourself at a proper value. Gosh~! I need to get about 40% raise to meet the median level of salary. 40% raise, huh?

I know money is not everything but when i found out all this today, I wasn't a very happy person. :( Ahhhh~~ I better prepare for the next negotiation session.