Prioritize, review, and adjust.
Chairs are required to juggle several types of priorities: strategic priorities for the department, daily or weekly priorities for the departmental office, and their own career development priorities. Schedule a special departmental meeting at least once a year to discuss strategic priorities such as curriculum reform, hiring plans, and degree programs. You need to have all permanent faculty engaged in setting the high-level priorities. Meet monthly, bi-weekly, or weekly with your staff to review office operations and make adjustments as needed. You may find that you need to meet more often early in your tenure as chair and less frequently as the staff becomes accustomed to your management style and performance expectations. Being intentional about setting priorities and making sure the entire department is aware of the priorities will help keep you focused and set the department on a positive trajectory.
Establish a routine.
Chairs need to have an open door more than 'regular' faculty members. But that doesn't mean you can't carve out chunks of quiet time for research or class preparation. Establishing a routine so faculty, staff, and students who need attention can predict office hours is advisable. If possible, remove yourself from the office for quiet times. Separating oneself physically from the office environment reduces interruptions and facilitates productivity.
Stop the paperwork ambushes.
It is also important to establish a firm policy regarding paperwork requiring signatures. A good procedure is to require that all paperwork be submitted to a staff member, who can screen the forms to make sure they are prepared correctly and present them for signatures once a day.
Tame your inner control freak.
While it might be tempting to take on all responsibilities, learning to delegate appropriately will prove invaluable. It will be good for you and for your department. Chairs should put forth the effort to engage faculty and staff in decision-making. The long-term gain will be a more effective and productive department, as well as staff and faculty members who are invested in the success of departmental endeavors.
Don't be afraid to ask for advice.
Because at times chairs might feel isolated, it is important to establish a support group. There are people throughout the university who can help--senior faculty members, other chairs, and associate deans.