Maybe you have a soft spot for animals. Maybe you and your loved ones have been affected by cancer or alcoholism or autism. Maybe you believe in being green. If you know what you care about most, you can be far more effective in your giving because you can concentrate your donations on causes you believe are most important.
In addition to helping you get the most satisfaction out of your charitable donations, such focus will help you be less likely to respond to pressure, grow your giving plan over time, and be a part of a charitable community with a common goal.