Many project managers start out as strong individual contributors, and end up as accidental project managers (filling in while the project manager is away, filling a need where a project manager is not available, etc).

Managing projects is a very different beast from being an individual contributor. Project managers must be able to delegate, direct, communicate, and coordinate (skills that are often the weak muscles of individual contributors). 

How can a new project manager best develop some of the skills that make a project manager successful as such? (I am especially interested recommendations on developing delegation skills. It can be tempting for a technical person to take on many project tasks themselves, rather than delegating to others on the project team.)