Almost all B2B sales are lost and won because of people. That's why the best sales organizations hire and retain the best even at a premium. To be the best sales engineers you not only have to be knowledgeable in your customer's business but also have enough social etiquette so that your prospects actually like you as a person.
While, we can treat our LinkedIn profile like a dating profile and list all the reasons why a person should trust us, that initial meeting and its human interaction will determine whether there is a professional fit. I stumbled across this article on "How to Look Smarter" on WSJ which should give almost everyone an "intellectual" edge in that first meeting.
As sales engineers (or any profession), don't do the stuff on the left, try to do the things on the right, but tackle the low hanging fruit in the middle. While projecting intellect is a good starting point; some prospects fear intellect. Here are my suggestions for recognizing those social queues: