When dealing with other functions such as Human Resources or Internal Audit, try asking the head of the function a simple question, “How do you think we could work together more effectively?”  An open-ended question like this, which specifically requests input from the other person can help to spring collaboration and to defuse any turf-war which may crop up.  Seek others advice on how to solve problems instead of festering in your own camp.  By engaging early, you can create better collaboration.