I used to advise companies on what to pay people. Here are 4 myths you should ignore when negotiating your salary.

• Gerta Malaj is a negotiation advisor who guides executives and mid-career professionals.
• Malaj previously worked at Salary.com, where she helped firms determine employee compensation.
• She warns against following common advice, like relying too much on market research or playing hard to get.

This as-told-to essay is based on a conversation with Gerta Malaj, who used to work at Salary.com and LinkedIn. She's now the cofounder of YourNegotiations.com. Her employment and identity have been verified by Business Insider. The following has been edited for length and clarity.

I'm a negotiation advisor, and my husband and I cofounded Yournegotiations.com. We help executives and mid-career professionals negotiate job offers and business deals.

I credit my negotiation expertise to a few things. First, I'm from Albania, which is a developing country. I had to navigate constrained resources my whole life. Second, I have a passion for behavioral science and psychology.

Third, I worked at Salary.com, where I advised companies on how to pay their employees. All of that experience has given me some hot takes on negotiations. Here are four common myths to disregard when negotiating your salary:

Rely on market research to figure out your salary

I worked at Salary.com and we had hundreds and thousands of data points filtered by industry, location, and company size. Those are three key variables that inform a company on how to pay someone.

Companies would pay us to present that data and tell them how much they should pay employees, and ultimately, many of them would go in a different direction than what we suggested.

If you're spending hours doing research on what companies are paying their employees, you're wasting your time. It often doesn't matter what other companies are paying because each firm has their own philosophy, and each team has their own budget.

The best thing people can do for themselves is get another offer to understand their market value. I recommend not having a number in mind. Even market data isn't one number, it's a range.

Negotiations are like playing cards — and conducting market research is like trying to look at the person's cards. You can never know the cards someone is holding. The best you can do is play your hand as well as possible.

Give a salary number

I recommend never giving a prospective employer a salary number, with very few exceptions.

Every role has its own budget that is informed beyond just the market data. It's informed by internal variables, like what budget they were approved for, if they're raising funding soon, or if someone critical has left and the company needs to fill the position quickly.

We can never really know a company's budget for a given role. So when you give a number and they accept it, you never know if there's money left on the table. If you overshoot above the budget, they may think you're entitled or that you won't be happy there with what they can give you and they might not take you to the final offer stage.

The only exception is if you already negotiated with the company and they didn't budge, and you have a better offer from somewhere else. However, you never want to lie about having another offer because recruiters can pick up on this. You also have to come up with a whole universe of lies and remember every detail.

Play it cool

I get clients who play hard to get, but that's actually the wrong move. When you interview, you actually want to show a lot of excitement, because that will offset the negotiation. That doesn't mean you should say "yes" immediately. The other party would rather you say "yes" and be done with it. But if you show a lot of excitement, you're offsetting the work you create for them.

Also, people want to work with people who want to be there.

Over-communicate

Over-communicating is the one quality that makes someone an amazing employee, but a bad negotiator. That may include sharing that you want to take a sabbatical, have kids, want to start your own company, or even talking about other interviews you've done.

You may want to over-communicate because there are stakeholders and you want to make sure everyone's aligned. But that can really can hurt you, because everything you say can be used against you. So you want to actually keep your heart close to your chest and not overshare.