Go online. Many sites can provide you with information about volunteering in your state.
Australian volunteer centres
Contact your local volunteer centre, too [all open in new windows].
Volunteering overseas
Check that the organisation really is not for profit.
Make sure the role of the organisation is clear. Can they provide you with satisfactory information about the organisation’s purpose?
Find out whether their funds are spent on activities stated in their mission statement.
Check that they have volunteer insurance.