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.