Multiple studies have shown that mirroring is an effective way to help build trust during any conversation. Subtle mimicry of body gestures, language, and facial expressions can establish a sense of rapport that smooths the way to consensus. Make sure to wait a few seconds before copying the other party, though, to avoid being noticed.
Give and Take
Find something to give away, and ask for something in return. Proper negotiation is, of course, all about the give-and-take, and lowering your ask can lead to a reciprocal shift from the other side. Just make sure you receive more than you offer.
Walk the other person through alternatives—but make sure they're worse than the one you're offering. By showing your co-negotiator other poor avenues, you can lower his or her expectations and make your proposition sound all the more enticing.
Look the Part
Part of getting anything done is proper presentation. A power suit never hurts, but the right subtle accessories that can help finish off your outfit, convey confidence, and pave over rough spots. A tie bar, a white crisp collar, cufflinks, a well-polished belt buckle—these little details make all the difference.
Leave the Ball in Their Court
As counterintuitive as it is, sometimes the best way to tie things up is to let go a little. If there is no deadline pressure on your end, give the other side time to consider and come up with a counter-proposal. Just be sure to leave them with your business card.