How to Hire Technical Writers: A Manager's Viewpoint 
Hiring technical writers is an infrequent but important part of a manager's job. Clearly defining the job and the required skills is the first step. Then use all of your networks to find candidates. Read résumés to find those that best match your requirements. The interview team needs to be prepared to ask relevant questions that verify and expand on the résumé and samples. Compare the interview team's evaluations, then check the references of your best one or two candidates, and make a prompt offer.
Huettner, Brenda P. and Ken Jackson. STC Proceedings (1996). Careers>Management>Writing>Technical Writing