Good will is not enough, so look at getting the skills that organisations need:
Technical knowledge is highly prized. Qualifications/experience in health (medicine, nutrition, speech therapy), finance and economics, engineering, environmental management and IT can make a real difference to development work at a local level
Learn a language. French, Spanish, Portuguese, Arabic, Russian and Mandarin would be useful for intergovernmental organisations and NGOs. Or a proven facility for picking up languages
Specialise. Work out what you want to do and start building your qualifications/experience in this area. It will give your applications more focus