Use Social Validation
People look to other people to decide how to behave, and whether or not to take action. This is called social validation. On FINCA's home page, and at other locations throughout the site, it would be very good to let visitors know that many people have already donated. This could be a total number of people ("Over 55,000 people have already donated to FINCA"), and/or combined with a dollar amount ("Over 5,000 people have donated a total of $275,000 to FINCA borrowers"). Including specific information like this would let the visitor know that many other people are donating. That message—that others are doing it—can trigger the visitor to do what everyone else is doing, and donate.
Although the site includes stories about FINCA clients, there's only one story or testimonial from the people who are donating, and this story is quite hidden in the information architecture of the site. If visitors coming to the site could look at pictures and read testimonials from the people who are donating, that would trigger the principle of social validation.