FORTUNE -- No one has to tell you that things are tough around the office. Ever since your team's headcount was slashed, you've put in extra hours and taken on additional projects without complaining. You deserve a raise, but in this time of constrained budgets, is it safe to ask? Fortune consulted Robert Barnett, senior partner at the law firm Williams & Connolly, based in Washington, D.C. In addition to his negotiating bona fides, he also helps prep presidential candidates for debates. But don't worry: You don't need Barack Obama's skills to get a raise.
Don't wait for a rebound
If you wait for the boom days, you may be waiting a long time. Make your move when you can prove that you are deserving with concrete examples of accomplishments, such as showing the weekends you have worked.
Timing is important
Most companies have a budgeting cycle; be aware of it. Come in two months before, not two weeks after, the company has made raise decisions. Do not ask on a Friday afternoon or before a vacation; your arguments will be long forgotten by the time your boss returns to work or presents your case to those above him. Do not ask during a crisis.
Prepare your case
Determine your best arguments, such as how hard you have worked, what you have accomplished, or how you have mentored others. Learn about the pay system and find out how discretionary decisions are made. Try to determine what others make. Anticipate your bosses' arguments.
Ask for help, not money
It's best to approach your boss for assistance rather than directly requesting cash: That way he is more likely to become your advocate. Say, "I would really appreciate your guidance on what I need to do to get a raise." Most people like to be mentors. Cultivate that instinct.
Live to fight another day
If you do not succeed, don't start a confrontation. Do not threaten to leave unless you are prepared to do so and have a place to go. Walk away in a friendly and amicable way. Your turn may come the next time around.
--Robert Barnett, Sr. Partner, Williams & Connolly is a contract negotiator for top execs at Deutsche Bank, Carlyle Group, and AT&T. He has also done publishing deals for Bill Clinton and Sarah Palin.