Do the homework on what other people in your field get, and compare what you get to the national average. Tell the company how you have saved them money in the past. Have concrete examples. I produced a 500 page book in-house and saved my boss thousands of dollars and a year time wise. Argue your case and SHOW them proof that the skills and abilities you bring to the job are worth more than they are currently paying you. You have to prove your case.

I made a point of showing the employer that I did my research about the company. I went on their website, googled their name to find news articles and tried to learn more about the individual who was interviewing me. She was impressed with that, and I got the job.