Illustration: Mark Matcho for Newsweek

Working part time can be good for your life and your checking account. But you need to know how to do it.

Louise Richardson of Parker, Colo., likes to work. But with four teenagers in her house and a firefighter for a husband, she prefers to do it part time. Through a placement service called 10 til 2, she landed a 15-hour-a-week job as an event planner. “It’s given us more financial freedom. My kids don’t see me as the person who cooks and cleans all day. But they also see that my family is my priority,” she says. “It allows you to have that balance between work and family.”

More than 25 million Americans—twice as many women as men—work part time. They’re moms, dads, retirees and people who are sick of the rat race. Employers are making it easier to work fewer hours: 36 percent now give employees the chance to work part time, according to a survey of 90 employers released last week by Hewitt Associates, a human-resources consulting company. The survey also found that 31 percent of employers now offer flextime, 46 percent permit job sharing and 39 percent allow telecommuting. TIP SHEET gives some tips on how to work part time successfully:

Know how to land the job. Make yourself “invaluable,” ideally first as a full-time employee, so your employer will want to keep you, says labor economist Myra Strober, who teaches a work and family course at Stanford University’s business school. Or call a placement service, like 10 til 2 (tentiltwo.com) or Mom Corps (momcorps.com).

Set ground rules up front. Define what “part time” means. If full-time workers typically put in 50-hour weeks, does that mean a half-time schedule requires 25 hours, not just 20? Many part-time jobs require some at-home work. Ask whether your employer will pay for your laptop or DSL connection. If you know you want to work less, or not at all, during your kids’ school vacations, request that schedule before you start the job. Beckye Young, an Atlanta mother of four, told her employer that she can work only from 9 until 2 p.m. so that she can get her kids to school and be waiting when they return.

Be flexible. “The flexibility needs to go both ways,” says Carol Sladek, principal of Hewitt’s work-life practice. Remember that if your employer lets you leave early to care for a sick child, then you should be willing to work a few extra hours.

Get paid fairly. “Work on an hourly basis. Then if the hours creep up, you need to say, ‘You need to pay me more’,” says Allison O’Kelly, founder and CEO of Mom Corps. “They can either decide to pay you more or decide to give you less work. You have more leverage.” Get it out of your head that “ ‘hourly’ means working at fast food,” says O’Kelly. “I have people who make $100 an hour.”

Be realistic. “Often, employers see women who work part time as less committed and less available for promotion,” says Strober. Ask your employer if you could ever get promoted—but don’t be surprised if the answer is no. “Typically you’re trading off pay, some of your benefits and quite often career progression,” says Sladek.

Communicate with family. “I explain to my kids that when they are done with school and they have moved out, I want to be able to continue with my career, and this is how you do it,” says Richardson. “Your whole family has to buy into this.” That’s particularly true for former stay-at-home moms, who may not be able to do as much cooking, cleaning and carpooling. With your family, plan ahead. “What’s going to happen during summer break? What’s going to happen if someone’s sick?” says O’Kelly.

Choose a part-time-friendly career. It’s tricky for tenure-track professors and attorneys to go part time. But it’s easier for nurses, doctors and accountants. “If you’ve got an hours-driven type of job, you can make it work more easily,” says Sladek. Target small, entrepreneurial businesses, which often prefer part-time workers. Remember to include volunteer work on your résumé, advises Jill Ater, cofounder of 10 til 2.

Consider flextime alternatives. Some part-time workers find that they end up working full time for part-time pay. To avoid this trap, Sladek suggests asking whether a full-time job can be made more flexible so you don’t even need to go part time. Will your employer compress your workweek into four 10-hour days, or let you telecommute more often? Dr. Marjorie Greenfield, author of “The Working Woman’s Pregnancy Book,” advises working whole days—but fewer of them. With half days, “the work drags into the afternoon, and you never get out.” she says

For a growing number of Americans, the trade-offs are worth it. Nikki Simon, 51, likes extra time to travel, walk her three dogs and hang out with her husband and her 20- and 22-year-old kids. A 9-to-5 job was out of the question—but so was staying home. “I just couldn’t clean the house every single day, and shopping wasn’t in the cards all the time,” she says. Now she works part time as a bookkeepers’ assistant and as a beginning real-estate agent. With her extra income, she doesn’t feel guilty now if shopping is in the cards some of the time.