Become conversant with the rules and regulations for your specialty. Become expert with the expectations of your employer.
Do not befriend your staff...mentor, support, and supervise them. Give them opportunity to share their knowledge, ideas, and dreams for your department...encourage them to participate in the development of your program.
Apply all rules evenly regardless of who is involved.
Always start from a position of support for your staff, your objective should not be to fire someone unless you have a history of reason (IMHO).
Remain calm. Make it your goal to respond rather than react to situations.