1. Take Nothing Personally and Always Remain Professional or Be Filled with Regret - When negotiating a salary, never take anything personally and always keep your calm even if you feel disrespected regarding the offer they give.

Not every hiring manager is effective at salary negotiation. As a matter of fact, most are on the same level as the job seeker, desperately wanting to come back victorious to their boss.

If you feel that you were lowballed, politely go over what you were expecting and why the offer came in as such. When treated reasonably, most people react in a reasonable manner.

If they don't respond reasonably, then you need to get a job at another company, as you don't want to associate yourself with such people.

2. The More Precise Your Background... the More Negotiation Leverage You May Have - It's the law of supply and demand.

There may be 12,000 competent sales professionals in Dallas, but how many are absolute experts when it comes to selling, for example, cloud computing services to Fortune 500 firms in the pharmaceutical industry? If you are unhappy with the offers you are getting, step back and figure out how to separate yourself from the pack.

This may take a little work, but no employer pays heavily for average, even in a great economy. Remember the following formula:

Expertise = Salary Negotiation Wiggle Room

Average = Consistently Under Compensation During Entire Career Duration

3. Ask Whether Re-negotiation Is Open In 6 months If You Prove Yourself... then

Prove yourself to be the best in the office. Let's say that you really want the job and while pay you offered is less than ideal, you can survive.

Politely ask if you could come back to the table in 180 days, as you are willing to prove that you can do what you said you could do during the interview. Work hard and, in 180 days, if played correctly, you will be leading the aforementioned conversations from here on in.

p.s. It doesn't hurt to ask for a performance report in 90 and 180 days. The more cards they show and the harder you work, the more lucrative your paycheck.