tips from Sheila Heen, an expert at negotiation and a teacher at Harvard Law School
Prepare. Know what you're worth in the marketplace. Don't think about how much you need, to pay off your credit card. Think about what you should be making based on your talents.
Don't ask for a raise, discuss it. Don't frame it as a yes or no question. Instead, have a conversation about adjusting your compensation to match your experience, duties, and/or workload.
Know when to walk away. Think about what will happen if your conversation doesn't go well, worst-case scenario. Think about starting a job hunt. Think about how you can improve yourself in your current position, so the next time you discuss a raise you have more weight behind you. Most importantly, if your boss says no, don't let it derail you. Be prepared for anything.