Two months ago, I wrote that you can’t write trust into an agreement. I explained why, but I didn’t go on to discuss how you could create trust between the parties.
Today, the folks over at E-Sourcing Forum provide a few good ideas. Learn them well, grasshopper.
LicensingHandbook Archive 
What you _can_ do is try to build activities and processes into the contract that, over time, generate trust as a byproduct. Toward that end, in many of my contracts I’ve been including a provision requiring periodic status conferences:
“(1) Each party will participate in conferences, by phone or in person, to review status and assumptions and to plan future actions, every X months or as reasonably requested by either party. (2) The parties anticipate that the agenda for such conferences will typically include, as appropriate and without limitation: • progress made; • problems encountered or anticipated; • plans for future action; and • assumptions being made. (3) Unless otherwise agreed, [Party X] will prepare and circulate a brief set of minutes summarizing (i) any decisions made, and, to aid in tracking, (ii) any action items assigned to specific individuals or parties.”
PS: As you might imagine, sales guys usually are not averse to the idea of required periodic status conferences with customers.