Communicating effectively when different objectives

First off I love this podcast. I am the classic example of how Mark and Mike talk about the "best welder being promoted to line supervisor" but not being a manager type. However after listening to the manager tools podcasts I have gone from leading a struggling area to having a very effective team - so much so my Managing Director asked me to fill in for him for a few days while he was away (bypassing Managers above me) I feel my communication with my team and to my upper management is currently good. What I still struggle with is getting my point across to Managers from other departments both at my level and above when they have different objectives. I sometimes struggle to get my point of view across effectively. What I need is advice on how to communicate when my objectives are different from other managers, how to formulate my communication to get my point of view across. Any advice.