It’s the $64000 question! I agree wholeheartedly with Blanca and Carl.
Still, for someone new to this, thought it might be useful if I spelled out more or less exactly what (I think) they are advising.
The specifics depend a lot on the person you’re asking. Still, it's possible to give some general advice. Bascially, you want to lay out the argument that investing in you makes good business sense for your company, and that paying you a better salary is the way to do it. Blanca describes this well.
As a rule of thumb, focus on the future. Your past accomplishments are best used as evidence that you are on track to become an even more valuable employee over the next few years. (You may feel that you should be rewarded for something you already did because it was great, but from the company's point of view, there's not much of an incentive: that already happened and you already performed well, without any extra money. A raise is an investment for the future.)
1. Gather as much information as possible. As Carl points out, the more you know the better about what others are being paid, what raises were asked for and which granted, how your boss feels you’re doing, how people doing your jobs in comparable companies are paid, how much discretion your boss actually has in determining your bonus, how quotas are set, etc. Make friends with others and compare notes. You may or may not decide to disclose what you know, but it will at the very least help you to set a realistic amount and to choose your timing.
2. Make sure your request is objectively reasonable. There is an art to choosing the right amount and the right time. A mentor in the company or in the industry can be very helpful here. If you do not have such a relationship, try to cultivate one (helpful for much more than raises).
3. Know your boss.
And now onto the more subtle stuff. Prepare to make your case:
4. What’s the context? If you are in a corporate culture where money is king and raises are a badge of honor, you will proceed very differently than if you are working for a small company, you have just bought a house and you would appreciate the long overdue raise to help with your mortgage payments.
5. What does your company consider most valuable? The most valued people in a company inevitably build on the work of many less visible people, and not everyone is going to get a raise. Just because you feel you are essential doesn’t mean this is obvious to others. Without seeming self-important, be ready to draw a clear line between what you do every day and what the company considers its most important work (your new implementation of the pie chart mechanism has cut the time of average report production by 15% resulting in an average 5% increase in productivity).
6. Prepare your argument objectively. Suppose that your current job is outsourced to a contractor X, and you are in charge of managing them. X tells you that they will need more money to do the job well. Now imagine that you had to present this request to your boss. You have no particular loyalty to X, but you think X is quite competent and would like to retain them. What arguments would you give pro or con? What reasoning can you imagine your boss accepting? Don’t forget now, you are being paid according to the company’s very subjective idea of your productive value, which is completely orthogonal to your being a valuable and worthy person.
7. Suppose the answer is “I would love to, but we don’t have the budget.” What would you accept instead of a raise? More responsibility? A higher profile? In-house training? How can the company invest in you? Also, perhaps you can get your boss to agree to concrete things you could focus on which would provide the most tangible benefit to the company, and which would, in his or her mind, put you on track for a raise in the future.
8. Don’t treat this as a big deal – this is crucial. Money is a very emotional issue for most people, and salary is a touchy subject. Bad feelings here can persist for years, and damage your reputation and relationship with your boss. You must be prepared to take no for an answer, and do it gracefully. Let asking for a raise be a painless process. You’ll want to do it regularly. Sometimes the answer will be yes (and if not, you might consider a new company).
9. Also, be prepared to accept yes gracefully. Thanks – I certainly appreciate it. That’s it. Why be so dramatic? You just argued that you were worth it and this was a fair increase; don’t give away the game by shrieking in surprise and ecstasy.
Good luck.