I have some organizations I support, but the majority of letters I get don’t get responses. I simply don’t have the money to do it. I donate to Bonei Olam whenever I can, and that is the main tzedaka I give to. There is a kollel program (I don’t remember what it’s called) that tests kollel guys on their learning, and pays a certain amount for a high score. I give to them because I know the money is going to guys who are really learning, not just in kollel because it’s the “thing to do”.
Here and there, I’ll give to some others also.