According to the latest data, the job market has strengthened to the point where many employers are having a tough time attracting and retaining qualified candidates.

Source: flickr user Evan Jackson.

In fact, according to Money magazine, about three-fourths of human resources departments say they are struggling to fill some positions, and 91% say this problem will get worse if the economic recovery continues.

In the new, stronger job market, a lot of employees may be inclined to ask for a raise from their current employer. If you think you're worth a little more than you're being paid, here are three ways to go about asking your boss for a raise.

Know what you're worth
Before you even walk into your boss' office and ask for a raise, do a little research and determine how much other professionals with similar jobs and experience are being paid. Not only will this give you some leverage to ask for more money, but it'll give you an idea of what you can realistically expect. The website Salary.com is a good place to start.

Source: 401kcalculator.org via Flickr.

For example, if the average worker with your job title earns $80,000 per year and you earn $85,000, you may not want to get your hopes too high. On the other hand, if you earn $65,000, you know you should be getting paid quite a bit more, and now you have the numbers to back it up.

Sell your importance to the company
When asking for a raise, it's all about selling yourself. Even if you've established that you are underpaid relative to other people with your job, the best way to convince your boss that you deserve more money is to highlight your strong job performance.

And don't just make the point that you do everything you're asked to do. You're supposed to do that. Highlight specific things you've accomplished that have been above and beyond what you had to do.

Be confident, and come armed with facts. Source: Flickr user bpsusf.

Most importantly, be confident. If you know you are worth more money, and have the facts to back it up, you shouldn't have anything to be unconfident about.

Time it right
Finally, when you ask for a raise, timing is everything. Conditions must be right to justify giving any employee a raise, so make sure to choose an opportune time.

Did your company just announce a blowout quarter? Maybe now is a good time to ask for some more money while spirits are high and your boss is optimistic about the future.

Also, a great time to ask for a raise is right after you did something that was particularly impressive or noteworthy. For example, if you just finished your big project two weeks ahead of schedule, it makes a great argument that giving you a raise would be a good investment.

On the other hand, if your company is struggling and losing money, it likely doesn't matter how good of an employee you are. If the money isn't there, you're not going to get it. And it's usually pretty easy to tell if things aren't going well. For example, if your company just did a round of layoffs, now is probably not the best time.

What not to do
For the sake of being thorough, as a former hiring manager, I'd like to share a few things you definitely don't want to do when you want a raise.

For starters, don't beg. Don't tell your boss a sob story that has nothing to do with your job. It's none of their concern that you have six kids or your mother-in-law just moved in. If you have lots of medical bills you can't pay, that's rough, but telling your boss makes you look desperate and like you have no legitimate value-related reason for wanting a raise.

Also, don't turn a raise request into a complaint session. Keep the attitude positive. Everyone has to do things at work they'd rather not do, and your boss is no exception.

Finally, whatever you do, don't make empty threats. Don't say "If I don't get a raise, I'm leaving," unless you're actually prepared to do so. If you don't get your way and then don't walk out the door, you lose any leverage you'll ever have when asking your boss for anything.