Show your worth
You may have worked hard, you may have been loyal to the company, but all that isn’t going to earn you a fatter paycheck. Prepare documents that show how your work and your personal ideas yielded results for the company (i.e. made them more money.) This is especially important to do if the person you’re speaking to doesn’t have the direct authority to give you the promotion, because those numbers will help them make a case for you when they talk to the person who can give you a promotion.