Goal Defender/Keeper
This position is a basic and vital position, stops the opposition from scoring and clears the ball if necessary.

The Mid Point Player
This position can be useful if played properly. The main purpose of this role is to intercept passes and stop any opposition from getting past.

The Attacker
This role is simple. Attack and shoot for goals. Do I really need to explain it?

Firstly, the playersUPDATE[/b]
Players and positions depend on the amount of players. In a team I prefer to have 1 of each position since the update changed it so only 3 people per team

The GameplanUPDATE
As the role entails, the attacker would go attack and score for goals. The midpoint player will stay in the middle and come back to help the goal defender. And lastly the goal defender will just defend the goal

Effectiveness
I've played with friends and this tactic is pretty damn effective, it is also really fun but it may get a bit tedious for the goal defender so you may want to switch it up a bit.