Define the role or function you need to fill as precisely as possible to get the best fit.
Along with members of your family, students are useful, untapped resource. Get in touch with your local college or university – if you have a relevant and interesting project they might even be able to work on it as part of their course.
Draw up a confidentiality agreement for every project and every person, whether they are part-time book-keeper, outsourced designer creating a logo or expenses-only intern. Make sure it is signed and up to date.