1. Never quit in a moment of emotion. Most people have moments—plenty of them—where they want to quit their jobs. Most of the time, the feeling passes. Give yourself a couple of weeks—if the feeling doesn't lift, then it's something you can take seriously. But you don't want to make a major decision in the heat of emotion that you can't reverse later. And remember, it's easy to reverse a decision not to quit. But it's close to impossible to reverse a resignation once you've given it.
2. Think carefully about the advantages of your job that you may not find somewhere else. Perhaps your employer gives you an enormous amount of flex time that you don't think you'd easily find elsewhere. Maybe you have a fantastically short commute that you really value. Maybe you get to do work that you love in a way that's hard to find. You need to figure out what's important to you and weigh that against what's frustrating you. Maybe quitting would be the right decision—but make sure that you've weighed all the pros and cons before you do.
3. If possible, talk to your boss about your frustrations. You may find that things can change.
4. Be realistic about what will happen after you quit. If you don't have another job lined up, how long will your savings last you? In this market, some people are going unemployed for a year or more, so if you resign without another job offer, you need to have a long-term plan.
5. Never quit just to "show them." Often a desire to quit in frustration really stems from feeling powerless. The employer-employee relationship has such a slanted power dynamic that when your job or manager is making you unhappy, sometimes it can feel like your only way to regain power is to quit—and then, that'll show 'em. But this is rarely satisfying. Your employer may be surprised at first, but people leave jobs all the time—they'll quickly get over it. And you don't want to be jobless just to make a point.
If you do end up deciding to quit, you'll feel a lot better knowing that you thought it through carefully and deliberately before you took the plunge.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the author of Managing to Change the World: The Nonprofit Leader's Guide to Getting Results and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development. She now teaches other managers how to manage for results.