The same way a non-expert should hire a good sailor, mercenary, sommelier, writer, butler, lawyer, guide, pilot, surgeon, mechanic, etc.

Find out who's regarded as knowledgeable and effective within their fields (preferably by people who know firsthand), be prepared to pay them well, tell them what you want done, and stay out of their way. Expect a certain measure of mild disdain when you clumsily tread on their domain, and listen to what they have to say.