In your previous position you did a great job. You were the recognized subject matter expert (SME), and now you have been promoted. Hopefully, you're smart enough to know the skills that made you a great team player won't necessarily make you a great supervisor. For any new supervisor, training is key to success in this role.
It's not enough to follow directions ... now you must give directions about what gets done, when, and by whom.
It's not enough that your projects are accurate and one time ... you have to help others keep their projects on track, and see that everyone works together.
It's not enough to focus only on your department ... suddenly you're a member of the management team. Your new peers will expect you to have a broader perspective, including other departments.
It's not enough to keep yourself motivated ... you have to be a coach, cheerleader, and "strong shoulder" to people who have bad days, conflicts with each other, and demands that you might not be able to satisfy.