Here are eight things you should never say when requesting a raise:
1. "Joe makes more money than I do, but we do the same work." While it's frustrating to see someone earning more money than you for doing the same work, salaries vary for all sorts of reasons: one person might have been a better negotiator than the other when first hired, or perhaps the job market was tighter, or maybe one has a particular degree or skill set that the company rewards, and on and on. Plus, managers typically don't respond well when employees use a coworker's salary as the basis for a raise request. Instead, focus on getting the pay you deserve for the work you're doing, independent of what your coworker makes.
2. "With a kid on the way, I really need to earn more." Your request needs to be about your value to the company, not about your finances. Employers don't pay people based on financial need; after all, the company isn't expected to pay more money for the same work to someone who buys a more expensive house and has higher mortgage payments. Stick to reasons that are about business and your value to the company.
3. "I'll quit without a raise." Don't threaten to leave if you don't get a raise. Even if it's true, you don't need to say this. Managers understand that this is the implied subtext when someone asks for a raise; it's definitely on their mind that they risk losing you if they can't do what you're asking. You don't need to spell it out. (Plus, if you make that threat and don't get the raise, you'll lose face if you don't follow through.)
4. "It's been a year since I had a raise." At many companies, you need to earn a raise; it's not always something that happens automatically year after year. While you can certainly point out how long it's been since your last raise, this shouldn't be the entirety of your argument. You also need to cite your accomplishments and increased value to the company.
5. "I meet all the requirements of my job." Meeting your job's requirements entitles you to the salary that you're currently earning. If you want more money, you need to increase your value by going beyond the basics.
6. "I just got a degree in (insert a subject that doesn't relate to your job)." Sometimes people think that earning a master's degree entitles them to a pay bump. But if the degree isn't going to directly contribute to your performance at work, it's unlikely that your employer will feel the same.
7. "Now that I've been here three months, can we revisit my salary?" If you've only been on the job a few months, you already did your salary negotiation—when you were hired. Generally, you want to have a solid year of work behind you before asking for a raise.
This rule includes a few exceptions, like if the job changes dramatically or if your responsibilities increase far beyond what was envisioned when you were hired, or if you're asked to take on new tasks that cause real hardship, such as constant travel. In these cases, it might be reasonable to revisit the question of your compensation sooner than a year.
8. "Since the company has laid people off, my workload has increased." When employers are going through a rough financial time, they're looking for places to cut costs, not add them. A lot of companies will freeze salaries during financially difficult times, and a smart employee will be sensitive to those constraints.
Source: http://money.usnews.com/