A contact at a medical device company recently asked me this question. The short answer? Preparation. Prepare documents, prepare yourself, prepare your team, prepare the vendor. This involves asking lots of questions of all parties involved.
Few medical device clients have instituted cross-departmental task forces to deal with translation or localization or multilingual labeling. For many departments, translation is a "black hole" and individuals do not understand what goes into a quality translation. Similarly, few translation managers prepare localization kits in support of their translations.
The person in charge of translations is sometimes not in the loop when it comes to product development schedules or engineering change orders. Requirements are thrown "over the transom" causing everybody downstream to switch into reactive mode. This then extends to the translation vendor who also does not receive any advance notice and is left to re-prioritize schedules and resources at a moment's notice.
While it sounds obvious, miscommunication and lack of preparation are often to blame when projects go awry.