Defending a play is much more important than attacking, so it's always good to cover a player while hez joining in a play.
For example, your defender made a run with the ball, so if your not involved with the play. Drop back and cover the defence. Don't leave the back empty because your gonna be prone to counter attacks.
So that's transition in defending, covering for a player.
Transition in attack, forming a triangle.
In futsal it may be hard because there's only 4 players in the pitch. In order to form a triangle, the middle man (attacking mid / centre mid) must always be in the middle of the triangle. The two defenders may join in or the forward and one defender while the other cover up.
Playing in a triangle gets you out of a sticky situation easily, therefore always play a 2-1-1 formation.