Before turning over your hard-earned and well-intentioned money to what you think is a worthy cause, check out what the Federal Trade Commission recommends.  Non profit organizations must be registered with Florida’s Department of Agriculture and Consumer Services.  You can check up on a charity’s registry by looking at the state’s gift giver’s guide, which will also tell you how much of the organization’s money goes to operating expenses and how much goes towards the mission of the charity.
For information on charities nationwide, make Guidestar your guide.  To report a fake charity, contact the Internal Revenue Service.