Here is some basic tips to playing team games.
1.The team that plays as a team best will win.
2. Have a plan going into the game that all are onboard with. This requires studying the board and determining your early objective and how
you will execute it.
3. Communicate with each other so that any deviation to the original plan can be moved on quickly.
4. Work together, work together, work together.
Team A vs, team B
These games are determined fast. If you play a good team expect war by day 4. Only take AIs that are to secure you defensively. The eastern end of Morocco comes to mind.
Multiple teams.
Here it is a little trickier. The main thing to remember is to try and keep a balance of power on the board. Don't let one team get too powerful that your team can't handle it. You may have to come to the aid of a losing team to ensure your success.
Remember these are just the basics, how you perform as a team will determine your success or failure.