PR in NGOs

In order to get PR exposure, i have gladly accepted to offer my services to a small NGO owned by a cousin of mine. But you will understand that apart from the theory package, i've got no practical experience in the field and it is quite a challenge but which could turn out as a good learning opporutnity for me; i have to be the 'window of the organisation to the outside world'. So i do i go about getting people or companies to donate and build a trusted and long-term relationship with them?

I will really welcome contributions from people in the field.

Thanks