Your role is not to tell your staff what to do - they should know what to do - or they need training
I have been asking people who worked with me over the length of my career “What did I do that allowed you to work well”. The answer was quite simple in the main, and quite consistent. When working for me, they knew what was needed, and I let them do it.
I defined the role, and let them get on with it - mentoring and coaching them where I needed to - so that the results were what I needed.
So how do you do this - it is easier to write this than it is in life, so feel free to ask me how you can do this.
What are the tasks - and what is the reason they are important - that your department needs to do?
What is the reason for your department to exist? (its purpose - along the lines of improving the tasks)
What is your Goals (your own goals - the goals for your department - and the goals for your own job - note these are different.)
How do you subdivide the tasks for your team, and set goals for the teams that align with the departments, your goals and the departments. (note: Tasks are SMART objectives, team objectives can be more open.)
For the individual - each person should have the task elements assigned to them, these are the SMART objectives - and they should be related to tasks. You can add an objective to support the team goals, but as the team goals are not really achievable - you cannot really put an objective saying that they need to be achieved.
Tasks - These are what your department does - this is the most important thing that managers forget. If the tasks are not done, the rest is not important - but the individual's objectives do not reflect any of the tasks.
Goals - these are more broad, to work together for the benefit of the company's clients. Something that is difficult to judge in the Dollar and cents style, but is the reason people come to work style.
The difference between tasks - what you are paid to do - and the goal - why you are paid to do it - is critically important. When the manager can tell you that - the staff are able to deliver just and will do what it takes. To find out more, just ask.