For me, what really makes for a successful team is clearly the people within that team. Communication is obviously key. Teamwork requires you to communicate effectively with others, recognising and understanding their viewpoints and appreciating the contribution you are expected to make. Communication is essential to good working relationships where each individual is working towards the achievement of shared aims and objectives. Trust is also a key factor to ensuring the success of working relationships, as is respect. If the team members trust and respect each other then they'll inevitably work well together towards their common goals.