There are several ways to help a Team improve its performance but they can be categorised as follows: 

Ensuring the Team has COMMON goals and purpose:  The performance of a Team that is ‘pulling in different directions’ will never be optimal; all Team members must know the product development and objectives and FULLY buy-in to them; no ‘ifs’ or ‘buts’

Ensuring the Team understands and embraces Shared Accountability:  We all understand self-accountability; you do something wrong and you pay the price.

Team Accountability or Shared Accountability is taking responsibility for others ie Team members must be aware of the work that others are doing and be prepared to challenge their work for the GOOD of the Team

Having a Working Agreement:  A Team Working Agreement states the ‘rules’ that the Team will follow to produce a valuable product; is something that the Team members discuss and agree; nobody ‘issues’ a Team Working Agreement to the Team.

The Agreement can contain ANYTHING that the Team would feel useful to enhance collaboration ie:

• Dates, times and places for the Sprint ceremonies
• How the Sprint ceremonies will be run
• Pair-programming arrangements
• How the ‘Definition of Done’ will be implemented
• Ensuring Psychological Safety:  Psychological safety is the belief that the individuals within the Team are safe for interpersonal risk taking ie a Team member must be able to be themselves and speak their mind without fear of negative CONSEQUENCES to their self-image, status or career.
• Adhering to the Scrum value of Respect produces Psychological Safety.