Valdis Dombrovskis, vice president of the European Commission and the European Union (EU) commissioner for financial-services policy is helping to drive through a new set of rules for Europe's financial sector.

If you always take the first salary offered — and never ask for a raise once you're happily toiling away for an employer — you're likely to wind up underpaid. Add in the fact that real wages are 7.5 percent lower than they were in 2006, and you can see how not negotiating salary can put you in a hole financially. But it's easy to say that everyone should negotiate, and harder to do it once you're seated at the conference table opposite a hiring manager or your boss. If you're anxious about asking for more — or scared that you'll ask in the wrong way — beware of these salary negotiation mistakes. Avoid them, and you'll be on the path to getting paid what you deserve. More from PayScale:

3 female former employees sue Google, alleging gender pay discrimination

Talk Like a Pirate Day: 5 modern pirate jobs

Are these the 7 worst bosses of all time?

1. Not negotiating in the first place

Only 43 percent of respondents to PayScale's survey reported ever asking for a raise in their current field — despite the fact that 75 percent of those who asked received some kind of pay increase. It's not hard to figure out why so many people held back: Asking for a raise is scary stuff. In fact, the majority of non-askers reported some sort of fear-based reason, from being scared of losing their job (8 percent), to being afraid of being perceived as pushy (19 percent), to being uncomfortable negotiating salary (28 percent).

But with 75 percent of askers getting more money, it's in your best interests to push through the fear. Not asking is probably the biggest salary negotiation mistake you can make.

2. Asking for what you want or need, not what the market will bear

Successful negotiations are based on data, not emotion. Now's not the time to talk about your increasing expenses or hurt feelings about a colleague's promotion. Getting a raise is all about figuring out the price you can command on the job market, and making a case for why you should be paid at that rate. In less than 10 minutes, PayScale's free Salary Survey can help you figure out how much your skills are worth. That's the first step in getting the raise you deserve.

3. Forgetting about bias

The myth is that women are paid less than men because they're less likely to ask for raises. In fact, PayScale's data show that women negotiate nearly as often as men (42 percent of women vs. 44 percent of men). However, they're less likely to get a raise when they do ask (26 percent of women vs. 23 percent of men reported not getting any increase). Further, research shows that both men and women judge female negotiators more harshly than male ones.

"In repeated studies, the social cost of negotiating for higher pay has been found to be greater for women than it is for men," writes Hannah Riley Bowles, director of the Women and Power Program at Harvard's Kennedy School of Government, at Harvard Business Review. "Men can certainly overplay their hand and alienate negotiating counterparts. However, in most published studies, the social cost of negotiating for pay is not significant for men, while it is significant for women." So, what's the answer? Some experts have suggested tying their salary request to a communal concern. For example, if your role involves negotiation, you might make the case that you must negotiate, in order to do your best work for the team. (Read more tips for women negotiators here.)

4. Not understanding the industry or the company's culture

A few years ago, a story made the rounds about a candidate who lost a job offer for a tenure-track position at a college, because she attempted to negotiate. Most of the experts who chimed in at Higher Ed were shocked that the college rescinded the offer without even attempting to negotiate; one academic job consultant weighed in with some advice: candidates should "negotiate offers, but with careful attention to tone and by tailoring their requests to the institution at hand." The vast majority of employers aren't going to pull a job offer just because you attempted to negotiate, provided you went about the conversation in a professional way. But it's worth making sure you understand the standards in your industry and at that particular organization, before you ask.

5. Going in without a plan