This is one of the most straightforward and common teams to build.
General Tasks / Elite Tasks
In order to get three stars in the you must: 1) Defeat all enemies, 2) Let no member of your team die, and 3) Finish the task quickly.
This is relatively self explanatory. You generally will want your strongest cards to perform these tasks, following the standard formula of 3 tanks up front, 3 damage dealers in back. The further you go into tasks, the more difficult the stages will be. You might find yourself needing to include a healer in order to keep your team alive in the later stages. With proper experimentation, you should be able to find a team that works for you.
The main difference between General Tasks and Elite Tasks is that Elite tasks require more physical points. Also the rewards are slightly different. However enemies in Elite tasks are stronger and you will come to a point where you maybe must first confrim with General Tasks before you continue to complete Elite Tasks.