There are six key common mistakes we project managers can make than can undermine our credibility with our team members during the lifetime of a project. They are:
Micro-managing
No body likes to have a ‘mom’ hanging over them at the work place. Sometimes you have to give a little faith to your team members when they say they will get a job done, and if need be – have a weekly or bi-weekly 1-2min update instead of a daily sync up.
Not acknowledging credit when it’s due
Recognizing the contribution of your team members and never take credit for someone’s work/ideas. Identifying your team members work and acknowledging it makes not only them feel good but everyone else.
Don’t have your team members back
Managers who do not stand up for their team members when unjustly chastised can result in loss of trust from their team members.
Breaking your word
Remember the quote, you are as good as your word. This can make and break your credibility with not only your team members but also your superiors. Promise what you can deliver and follow through.
Not Listening
No one likes to repeat themselves. Ask what you don’t know, listen well, get it all down. If you keep coming back again and again to ask the same question, not only you are slowing progress in your team but your showing your incompetence as a project manager on a task you clearly know very little about.
Ineffective Communication
Effective communication is quintessential when it comes to being a project manager. When you share any information with you team, make sure you have all the facts and if anything changes (goal, objective, scope, resources), convey the message to your team member and explain to them clearly.
—Added 2 more I found from personal experience—
Resistance is Futile
With every project comes new experience not just for yourself but for your team members. Being open to these experience can be healthy not just for yourself but also for those involved in current and future projects.
Favortism
No one likes working for a Project Manager where they know there is little opportunity for growth because of obvious favortism in one of the team members. Share the tasks equaly and give each member the opportunity to shine.
Post can also be found on http://www.projectmanagers.net/profiles/blogs/six-common-mistakes-project

Keep up the content.
I meant keep up with the content.