Linda Babcock and Sara Laschever, authors of Women Don’t Ask, write that women who do not consistently negotiate their salary increases, may earn less that their female colleagues by up to $1 million during their careers, than those women who do negotiate.

Women generally don’t ask for pay raises as often as men do, and when they do, they are not as successful at it as men.

Women tend to negotiate differently to men, if we get knocked back when asking for a raise, or if we hear about someone else who has asked but was rejected, it may deter us from trying.

The underlying issue is women work hard and wait to be noticed. We don’t ask for the assignments and we don’t ask for the promotion or the raise. As women we must be more assertive and put our hand up.

The following are three tips on asking for a raise from Linda Descano, President and CEO of Women and Co.

Research

First, learn where you are situated in the compensation structure of your company. Some large companies and most government and unionised workplaces publicize salary ranges. If such information is not available, ask your manager what the range is for your position, if there is upside potential, and/or if you would need to be promoted to increase your salary.

Next, get a general idea of what the market pays for your job. Salary information is available on various websites, as well as through executive recruiters and professional associations. Consider whether there are good reasons why the salaries quotes differ from yours, such as non-salary benefits or corporate culture.

Finally, check with your manager, human resources department, and on your company’s internal website to find out what types of compensation your company offers in addition to salary, including performance bonuses, stock options, restricted stock, and benefits. Ask about your company’s compensation policies. For instance, your boss may have discretion to give bonuses, but no power to offer more vacation time. You’re more likely to meet with success if you ask for compensation that fits within your company’s existing practices and policies.

Perform a self-assessment

To get an above-average raise or starting salary, you need to be an above-average performer. Be honest with yourself. Ask a co-worker to evaluate your strengths and weaknesses. But if you do ask, be open to his or her feedback.

Be sure to document your accomplishments in terms that justify a raise or higher starting salary. If you’ve exceeded targets, state how much additional money you’ve made for the company. If you’ve taken on responsibilities that belong to a higher-level job, point out your extra service. If you have implemented company policies that have helped to cut costs, describe and quantify the savings realised.

Ask for it

Know how much more you want to earn and in what form, generally salary, bonus, or equity. Also, think about what you would like if you can’t be paid more, such as additional training, flex time or a company car.

Be sure to choose the right time to approach your boss. This is likely to be before your annual performance review. (Find out if your company separates salary and performance reviews.) Often, by the time your review rolls around, your boss has already determined your raise. If your company doesn’t have a formal review process or it’s too far away, you can sit down with your boss after the successful completion of a project.

Finally, if your request is denied, don’t give up. Find out why and set a date to review your situation again.

This article first appeared on Women in the Black.

Tamia Gallego is the founder and director of Women in the Black.