What advice would you give a new IT project manager?

TechRepublic is asking veteran IT project managers to share advice for newbie PMs. Please post recommended skills and resources and what not to do in this project management discussion.

Experienced IT project managers, what career advice would you offer someone who is just starting out in project management? For instance, what skills do you think every project manager should master? What are the rookie mistakes that many project managers make when they're starting out? What books or online resources would be invaluable for a new PM?

Basically, what do you wish you had known when you were learning the ropes in IT project management? Please share your words of wisdom in this discussion.