Good Staff Work - that seems to be a black art taught mainly in the military or government.
Simply put, a staff is a group of peers who report to the same boss.
Large staffs can get very complex with a chief, primary staff, and special staff. Many times, people can end up on a staff without even realizing it.
Each staff member is the resident expert in his or her field. Their job is to make recommendations to the boss with alternative courses of action.
Good staff members can break down their recommendations clearly in meetings or, when written, they can brake down complex decisions into point papers.
A point paper has three key sections: topic, discussion, and recommendations. It can be as short as a couple paragraphs or as long as several pages prefaced with a background section and in depth recommendations weighing the costs of each choice (time, money, resources, etc) in the context of maintaining a responsibility to either the short, mid, or long term.
Great staff members are the people who can fully support the boss' decision when the choice made is not the one at the top of the staff member's list.