How to launch a second career that gives back

FORTUNE -- Dear Annie: After 38 years in financial management, I'll be retiring at the end of this year, but I hope to be working just as hard at something new. My wife and I (and our two daughters) are avid amateur musicians who each got our start through music classes in our public schools.

Now, because of state and local budget cuts, local music programs are all but disappearing. Drawing partly on our experience and connections in the business world, we want to figure out how to start a nonprofit that would raise money to buy musical instruments, hire music teachers, and put music lessons back in the curriculum. I know that charitable giving overall has been battered by the recession, so maybe the timing is bad. Your thoughts? --Piano Man

Dear Piano Man: It may interest you to know that you're part of an enormous trend that has been picking up for the past few years: A desire among retirees to keep working, but in different careers, that help their communities.

Marc Freedman, founder of a nonprofit called Civic Ventures, coined the phrase "encore careers" to describe these second (or even third) callings.

Almost half (45%) of working adults ages 44 to 70 say they want to pursue an encore career in retirement, according to a study Civic Ventures conducted with the MetLife Foundation. Another 6% in the same age group, or 5.3 million people, are already doing so. Of those, most (70%) work in education, health care, and government agencies, and 60% put in 40 hours or more per week.

By zeroing in on putting music back in your local public schools, you have set yourself a tough challenge.

"Funding an arts organization is always painful. Starting one in this economy is going to be excruciating," says Marci Alboher, a vice president at Civic Ventures.

That doesn't mean it can't be done.

Talkback: Have you considered changing to a more community-service-oriented career? Leave your comments at the bottom of this story.

Consider, for example, Fresh Artists, which has delivered more than $100,000 in art supplies to cash-strapped Philadelphia public schools since 2008. The group was started by executive director Barbara Chandler Allen, who set out to pair local corporations like Comcast -- which had acres of bland, empty office and conference-room walls to fill -- with student artists, who would donate bold, colorful paintings in exchange for corporate support of Fresh Artists' programs.

Allen's tips on how to get a new nonprofit off the ground:

1. Find a need. "Don't approach it as starting a 'charity'," Allen advises. "What you are doing is identifying a need and marshalling resources to fill it." In the case of Fresh Artists, schools and companies each get something they value. Try to design your organization along similar lines.

2. Connect with others. Allen suggests setting up Google news alerts, seeking out Facebook and LinkedIn groups, and connecting in any other way you can find with others who may already be working on similar projects in other cities. They can provide encouragement, and maybe keep you from reinventing the wheel.

3. Volunteer or intern at a nonprofit. "Spend at least two months learning best practices at a successful nonprofit," Allen suggests. In addition, take some classes in nonprofit management, even if you just audit them for no credit. "You need to rub elbows with people in the nonprofit community," Allen says. "Taking a class can also be a good way to meet mentors."

4. Write a business plan. "Research the market just as you would for a new business," says Allen. Talk with your potential "customers." Don't forget to assess the competition: What other organizations in your area are competing for scarce arts dollars, and how are they doing it?

5. Line up a CPA and an attorney with nonprofit experience. "This is crucial," Allen says. "You really need people who know the tax laws and other laws governing nonprofits, which are very different from those that apply to businesses. Otherwise you can run into serious trouble."

6. Set up an advisory board. Allen recommends that this group consist of about half experienced nonprofit managers and half "businesspeople and creative people who can bring lots of fresh ideas to the table." You can also have a separate, smaller board of directors, as Fresh Artists does, but your advisory board is a more informal team of supporters whose expertise you can tap when you need it.

Of course, not everyone who decides to embark on an encore career wants to start a nonprofit. For those who aspire to go from the corporate world into, for instance, teaching or some other form of service-oriented work, a terrific "Get Started Guide" is available at no cost at encore.org. It includes information on how to choose an encore career and how to finance the transition, along with case studies of people who have done it.

Good luck!

Talkback: Have you considered changing to a more community-service-oriented career? Would you wait until you retire, or do it sooner? Tell us on Facebook, below.