How can I be sure a given translator is reliable?

Consider the professionals' training and degrees, years in the field, credentials earned, membership in professional associations, references, etc. Professional experience outside of translation may also be relevant. You may want to discuss the content of your job with the translator in order to assess their understanding of the material. It is not unusual for a client to ask for a short excerpt from a job--100 words or so should be enough to get an idea--before assigning work to a new translator. (Note that some translators include samples of their work in their profile 'portfolios'. In addition, looking at a translators' KudoZ history is sometimes useful in understanding a translators' style or approach to terminology.)

You may want to consider working with a ProZ.com Certified PRO or find a pre-screened provider in a ProZ.com Pool.