This is an issue because some charities spend more than others on things like salaries and overhead and fundraising. Unless the entire charity is staffed by religious, you do need to spend some on salaries because the people working there deserve to make a living wage. Obviously some overhead costs have to be paid (utilities, postage, etc). Fundraising is the issue that bothers me the most because it can be very expensive for a small return. On the otherhand, those direct mail letters with the plastic rosaries in them are much cheaper than you’d expect.
I think the best way to give is first to set aside in your budget how much you will give. Then from that make 3 ‘pots’–1 for your parish, 1 for your designated charity, and 1 smaller amount for random gifts.
Pick a cause you’d like to support–say pro-life issues and investigate several charities that work in that area. Ask them for financial paperwork etc. Then select 1 or maybe 2 that will be your main charities. Focus your giving on them. If you can, let them know you’ll give a set amount each month or year, that will help them to budget and lower their overhead costs also.
Then, throw all the other things that come in the mail away. You can save the medals and rosaries to give to your CCD program, but you are under no obligation to give to every charity. If something catches your eye, you can give a small amount from your random gifts budget. You can also use that money for the special offering a church or when you see a beggar in the street.
But budgeting an amount and picking a specific group or 2 to spend it on, you may find that you can become even more generous!