Wise Giving
To cut the IRS's share of your 2013 income, consider donating to a charity before January 1.
Make your money count. Donate to obscure ones that do not have lots of donors. This way, you make your gift do more work. Your gift is more important.
Before you decide, use this service: http://www.charitynavigator.org
You can see if the organization is a good steward.
If you mail a check, get a receipt from the Post Office. Buy a receipt and a postage stamp, fill out the receipt, stamp it, and get it canceled. This proves that you mailed it this year. Or mail it "return receipt requested."