I've given money to both charities and people. Here's the thing about donating, though: you'll get on all sorts of mailing lists and shit, and you'll get lots more begging letters, emails, phone calls and texts. You know those PBS/NPR donation drives, where they're like "We just need ten more donors this hour, it doesn't matter how much!" or those charities that send you pre-printed labels and say "Hey, just send us five bucks, that's all we need"? Yeah, they're harvesting your information. If you even send them a penny, they'll be back for more, and they'll sell or trade your information to other charities.
I give money to our local volunteer fire/ems department every year, but I don't use their pre-printed mailer; I hand them cash when Santa Claus and the Easter Bunny come through on their trucks. I have one of those pre-paid Visa gift cards that aren't tied to an actual person; if I do an online donation, I'll use that and give them fake information. The money is legit, the information is good enough to pass, but they can't come harass me for more.
This includes all donations, by the way - political, religious, civic, charity, social, whatever. Do it in cash or by an anonymous Visa gift card.