I think it all comes down to communication and accountability. The team should have some sort of idea what the others are working on. Another thing of the key characteristics of an effective project team is that the team members have the talent, knowledge and familiarity necessary to accomplish the undertakings assigned to them.
Also, networking or communications: effective project team members know how to express themselves in a way that gets their point across without offending others. They also know how to effectively listen when others are expressing thoughts, opinions and ideas. Also, creative thinkers are especially helpful during the project.Finally, members of an effective project team should have positive influence over their peers.