In the U.S., 40% of new managers fail to manage well and are dismissed.

Greg McDonald, in his article in Martesfinanciero.com, reviews the major mistakes made by novice managers.

The new role is not clarified.
You may be given a formal description of your job / position and even have a brief chat with your new boss. But this is not enough. First of all, you need to make sure you know exactly what the expectations are and what results are expected to be achieved.

Managing without leadership.
These two are not the same. Leadership is more than just running things or having the last word. Or as Richard Branson puts it: "being bossy is not a desirable attribute in a manager or anyone else."

Failure to gain the staff’s trust and respect.
Just because you have a new title it does not automatically give you the trust and respect you need. These have to be deserved and earned. You must demonstrate your own character, competence and skills first.

Failure to manage and focus on objectives and your share of the work.
Remember, your main objective in this new position is to achieve results for the organization. To achieve this, you need to build a strong and united team, and manage your time effectively.

Failure to manage relationships with subordinates, peers and those at higher levels.
You must learn to communicate and relate effectively: up, down and sideways. And learn to listen more than talk.

Source: martesfinanciero.com