When considering whether to retain a consultant, an organization should first have a clear understanding of what they really want from a consultant, and what assistance a consultant can actually provide. There are three main roles that an effective consultant can play.
1) As "a pair of hands," a consultant can do tasks that a client organization knows how to do itself, but does not have the staff to accomplish (e.g., organizing meetings, drafting documents, conducting interviews with clients, and other such hands-on work.
2) In the "expert" role, a consultant provides knowledge or skills that the organization does not have in-house (e.g., doing an evaluation of a management function, providing an analysis of the implications of a major building effort, etc.).
3) In the "collaborative" role, the consultant works as a partner with the organization, contributing process knowledge, but leaving the rest to the client, who has the task expertise and staff to accomplish tasks once the approach is determined (e.g., providing guidance on the planning process and facilitating planning meetings and retreats, while clearly leaving the content debate to the client).
Typically, a consultant proves most helpful to an organization when offering a combination of all three roles with the emphasis on the collaborative role, the consultant can significantly add to the productivity and continuity of the planning process.
If no one in an organization has experience with planning, then a consultant's assistance with designing and managing an effective process will help focus staff energy where it is most needed and preclude their wasting time reinventing the wheel.
Also, an outside person working with the group offers objectivity and neutrality. Sometimes it takes an outsider to ask the hard or dumb questions, and a skilled consultant will help surface disagreements about important issues, as well as manage potential conflicts in a constructive way.
In choosing a consultant, an organization must also look for "fit." A consultant may have all the expertise one could ask for, but still should not be hired unless leaders/staff truly have confidence in the person. The consultant must be both a good listener and not afraid to speak honestly. Many important issues will be discussed in the planning process, perhaps including delicate issues that demand discretion or could arouse conflict -- so, a good, trusting working relationship between the consultant and the organization is crucial to a successful planning process.