If you are planning to volunteer in Nepal you should research the legitimacy of any organisations you are planning to use. The Social Service Council of the Government of Nepal maintains a list of legitimate volunteer organisations email: firstname.lastname@example.org. If you are volunteering at orphanages which are profit orientated organisations rather than charities you could be contributing to child exploitation. Contact the Nepali Central Child Welfare Board for confirmation before signing up to volunteer for such organisations.
Voluntary Services Overseas (VSO) has been running volunteering programmes in Nepal since 1964.