None of us will deny that most of project management involves the act of getting things done through the skills and efforts of other people - mainly your project team members. Since that is the case, your ability to influence, oversee, assign, delegate, and supervise others is critical. Since this is true, the project manager's interpersonal skills are of immeasurable value. Closely tied to your interpersonal skills are your behavioral skills: your personal conduct, style, and approach. Together, these two skill sets are often called the 'soft skills.” Some examples of soft skills that most project managers need to possess in order to be successful:
Team and individual leadership
The ability to lead individuals on your team and within the organization is critical as is the ability to lead a cohesive team and direct them on a long-term project toward a successful conclusion.
Oral and written communication
Communication is #1 for the project manager - that's always been my personal belief and stance. Keep the team and customer well informed, keep the communication flowing on the project, and communicate well with your executive leadership and no one gets hurt.
Conflict resolution
There will always be differences to resolve. The longer the engagement the more differences there are to resolve and the more likelihood that you could have a larger conflict or issue arise. The skilled PM must have conflict resolution skills and be able to settle differences that arise on the team and with the customer. Be considerate, but be firm because project success may be at stake.
Negotiation
The PM must have good negotiation skills. Change orders come to mind as the key areas of negotiation with the customer. But there are other areas that may require negotiation such as resource availability, technology decisions, travel needs, etc. The busy project manager will find themselves negotiating more than they even realize.
Influencing
A well-connected PM will have very useful influence over certain key personnel and departments in their own organization. This helps knock down roadblocks during the project and helps acquire critical information or resources to complete the project.
Delegating
The PM who fails to delegate either fails, does most of the work themselves, or - likely - both. Learn to delegate - it's a key part of being a project manager. Most of your time should be spend directing others, not doing each project task.