For client-agency relationships to thrive, planning ahead is key.

"Plans tell you what you're trying to accomplish, who you want to reach, what you want them to do, and how you'll know if it worked," explains Dawn Wilcox, Allison & Partners' Los Angeles general manager.

Whether the plan is for a one-time project or a long-term program, she says, setting targets and goals provides both agency and client "with a road map ... and holds everyone accountable."

That advance-planning "road map" ...