The number of workers who have never asked their employers for a raise might be surprising. A recent survey has revealed that at least 57 percent of women workers and 46 percent of male workers have not asked their bosses for a salary increase due to fear, according to Glamour Magazine.

In most cases, workers rely on annual increases that comes automatically for many companies. "But that's the exception rather than the rule these days," said Don Kelly, a human resources executive, according to The Street. "Getting a raise is showing that your net worth to the company makes you more valuable than you used to be," Kelly added. The executive said there's also a right way and a right time to do this.

Below are some tips to asking the boss for a raise:

1. Check for current rates of your job at Glassdoor so that you'll get an idea of how much to ask for. However, don't tell your boss you know how much people in your field are making.

2. After doing the comparisons, make sure to back-up your case. You can't simply march up to your boss and say you deserve an increase since your rates went up. "Align your argument and rationale with the performance of the business and the goals of the company," said Jim Weiss, the founder of W20 Group, via PR Week.

3. Assess your own performance and be honest about deserving a raise. According to Kelly, you have to consider these points before talking to the boss: if you've saved your company money, if you've improved your system, or if you delivered work efficiently and faster. If you believe you haven't been a valuable asset to the company, then make sure to work at being one first before asking a raise.

An asset is "someone who has engendered positive change, brought great people and clients into the company, and is getting kudos from clients," said Weiss.

4. Throughout the year, ask your boss feedback about your performance to help you assess your strengths and weaknesses. Your boss will also appreciate you better for doing this. "When someone comes to me passively and asks about the business, I think, 'This is the kind of person I want to invest in because they want to know how we grow and how we don't,'" said Grace Leong, CEO of Hunter Public Relations, via PR Week.