You have a deadline looming, and it's not Christmas.
This month is your last chance to make charitable donations for 2013. So in between the holiday parties and cookie swaps, consider pulling out your checkbook one more time for your favorite cause.
You'll have plenty of company. Most charities report receiving about 40 percent of all their donations in December, according to a Charity Navigator poll.
Charitable giving is always ennobling, but this year there are also ways to make it as effective as possible. If you maximize your charity tax deduction, you can give more, and if you embrace novel ways of working with a charity, your generosity can also have more impact.
(Read more: It's the way you donate that counts)
Investors have several options this year for taking full advantage of the tax breaks for charitable donations.
For starters, the stock market's strength in 2013 means many investors are sitting on hefty capital gains. If you donate some of that appreciated stock to a charity, you can take a deduction for the fair market value. You also avoid paying capital gains on the stock's appreciation—a nice twofer in a year when taxpayers in the top bracket are facing a higher capital gains tax rate.
(Read more: U.S. stocks finish higher on the week)
If you are over age 70½ and receiving a required distribution from your IRA, you have another option. You can donate up to $100,000 of that amount and it will not count as income. (This tax break is due to expire at the end of the year, so if you are planning to make use of it, this is the time.)
"Defer revenue and accelerate deductions if you can, especially in high tax brackets," said Mark Steber, chief tax officer at Jackson Hewitt. "Rates are going to be pretty high" in the new year.
As for how you seek out the organization that will do the most good with your donation, the landscape is shifting, according to Susan Wolff Ditkoff, co-head of the philanthropy practice at Bridgespan Group, an advisor to nonprofits and philanthropists.
"Individual donors, certainly more than 10 years ago, are going directly to the nonprofits that they care a lot about. It used to be they would go through an intermediary like the United Way," she said.
The Internet, of course, makes finding a charity easier. And with websites like crowdrise.com creating communities around charitable causes, you can find other like minded donors online and perhaps learn of more organizations with missions that dovetail with your charity goals, where your gift may make even more of a difference.
(Read more: Charities get holiday boost from crowdfunding)
Ditkoff also advises a careful look at whether your charity of choice is on an upward trend. "One of the first things we advise people to do after they pick their passions is to look for organizations that show evidence that they're learning," she said. "Some organizations do a terrific job of demonstrating one or two heartwarming stories. But when you look at how their programs are working, it doesn't necessarily add up to programmatic improvement. Are they actually improving their programs based on data?"
Some of the charity rating organizations, like Charity Navigator, include measurements of the percentage of donations charities spend on overhead versus programs. Ditkoff warns against choosing a charity for its low overhead, however.
There is, she said, a "myth that the overhead rate has to be as small as possible. What that means is they're not investing in things like evaluating their programs, information technology systems that would make them more efficient in the long run." Better, she said, to focus on organizations that are "investing wisely in overhead."
Your philanthropy will also be more successful the more you get to know the organizations you are supporting. If you are a major donor, you can certainly get in touch with an organization's top officers and discuss your goals. But even those giving less can get to know organizations by volunteering for them.
"If you have marketing skills or financial skills, working with the organization is a terrific way to get to know them," Ditkoff said.
David Rosenberg, president of iWeiss Theatrical Solutions, a company that makes theatrical drapes and rigging, gives both time and money to Friends of Karen, a charity that provides a range of support for families with critically ill children. He got involved after attending a Friends of Karen benefit, and is now on the board.
"I see all my friends' kids and they're healthy and active and have all these opportunities. Then you see these kids who are sick, and they can't do any of that, and I just find it emotionally brutal," he said. The size of Friends of Karen also appealed to him. "I donate money to other organizations, but this just seemed small enough that your donation has an effect."
It's not just Rosenberg's financial donations that help. He has introduced friends to the organization as well, and one family gave a sizable challenge grant that enabled Friends of Karen to launch a new support program for siblings of critically ill children. The program now has two full time staffers and supports 100 children.
"Your individual work has a lot of impact," he said.
—By CNBC's Kelley Holland. Follow her on Twitter @KKelleyHolland.