You deserve a raise. Women are paid less than men, plus size people are paid less than their skinnier colleagues, and your ethnicity may be a factor as well. And yet you won't get anywhere by marching into the boss' office and pointing out that you make a lot less than Stu, the guy with the same job title as you but half the workload.
Toot Your Own Horn
People get paid according to how much money they make (or save) for their employers. This is why baseball players make millions of dollars while firefighters do not. You may spend your day putting out metaphorical fires. The entire department may fall apart in your absence. And yet the big bosses aren't thinking about how they need to throw lots of money at you to keep you happy and not job hunting.
You may not be able to translate your job performance in terms of money, but your wins are still valuable. If you improved your team's efficiency, that translates to savings or increased earnings depending on the work. If you figured out how to solve a problem, took on new responsibilities, or did something that your colleagues wouldn't have been able to pull off - that's value you've brought to your employer.
Write these things down so that you can remind your boss about them when the time comes. It's also a good idea just to keep track of all your projects and responsibilities so that you can easily update your resume some day.
Lay The Groundwork
How do you lay the groundwork for a raise? It's not by emailing articles about pay disparity to your manager. It's a move even gutsier than that - taking credit for your successes. If one of the bigwigs gives you a compliment, accept it. Say, "thank you," and bask and the acknowledgement of your awesomeness. No modesty. No, "I got lucky." You did those things. Own it. Don't discount your team if you have one, but don't give them all the credit. "I couldn't have done it without my team," is different from "my team deserves all the credit."
Timing Is Everything
Even though you're going to be prepared for the conversation, be flexible about when it happens. You want to catch your manager in a good mood instead of when they're dealing with ten different crises at once.
If your employer hands out raises at annual performance review time, you want to speak to your boss while they're writing everyone's reviews. When you meet with them to go over your review, three levels of upper management have already signed off on your review and annual increase. It would be a huge hassle for your boss to go back at this point and get you more money.
If your company doesn't have regularly scheduled reviews and raises, you don't want to ask for a raise every six months. But once a year is fair. If you score a major victory at work - bring in a new client, solve a problem, create a new procedure - that's an excellent time to approach your manager about a raise.
Dress The Part
Well made, well fitting clothes can go a long way towards counteracting your boss' unconscious biases. Wearing an outfit that projects competence can soften them up and give you the confidence to make your case. You can't go wrong with Navy, and a Blazer is always a good idea in this situation.
This Is Not A Big Deal
Asking for a raise is a perfectly normal part of any job. Fielding these requests is part of your manager's job. They might say no, but they're not going to punish you for asking.