For starters, create an e-mail/Outlook folder, and call it your praise folder. Any positive feedback, both internally and externally, file it in this folder, so come performance review time etc, pull out those well deserved accolades. This will give you a good cause to negotiate a pay raise. Also, research the market, and think carefully about how you already have, and how you will add even more value to your employers business to produce tangible results.
Prepare Prepare Prepare. If you go into into negotiations unprepared you will look like you aren't taking it seriously yourself. Try to present your case in the best life so that they can't possibly turn you down. Do your research; find out what you should be getting paid...does your company use market match data to plot what salary scale you should be on. Where do you sit on such a scale? Or look externally at the market to see what you should be getting paid? Are you paid based on performance? Are you an outstanding performer; do you deserve a pay rise. If pay rises are performance based, make sure you state your case regarding how you have performed in the last few years. Ideally, don't issue ultimatums such as give me more money or I'll walk. Instead explain why you feel you deserve a pay rise, and keep to a few facts and statements.
In addition to what Justine said, it is important to remember that if you wont ask for it you wont get it. So before you have the talk prepare yourself and rehearse you would broach the issue with the boss.
Research, preparation and a solid business case are critical to getting what you want in business- including a salary increase. Don't expect to be paid more just because you are doing a good job. After all the business reality is that is how companies make money- by having good people do great work and paying them a market based wage.
The key is to be a bit creative and back up you business case with fact. Demonstrate how you have contributed to the bottom line, show where you current salary compares to the market. Look at ways to increase your total pay through other items like investment in training, bonus structures that are linked to performance, or other one-off payments.
Most importantly, check your emotions at the door and treat this as a buisness decision- not a validation of your personal worth. Be fair in what you ask for, document everything and never try to threaten your boss that you will leave. Have confidence in yourself and the strength of the information that you have prepared and a good employer will take notice and work with you to acheive a postive outcome.