This is something that I've struggled with for a long time. I really don't donate to charity outside of clothing to a second hand store that donates to a charity. A few times a year, people will ask me for donations and I happily comply.
My employer matches dollar for dollar for donations made to our local United Way. United Way sent somebody to talk to us about it at work. They will even automatically withdraw the money from our paychecks throughout the year. I decided to donate $250. It actually came out to $252 over the course of the year. It is $10.50 per paycheck. It's not a lot of money but I hope that it will help United Way in my area.