I find when playing ranked doubles (Gold 2) with my friend that we are often out of position and vulnerable to counter-attacks. We alternate between a "one-attacking-one-defending" tactic and a "passing" tactic (where we direct the ball towards either each other or the enemy goal). Watching various streamers doesn't really help because their skill level is so high that they often don't seem to pay attention to positioning tactics but get away with it with really cool touches, jukes, aerial goals and dribbling but for us common folk without thousands of hours in the game what positioning allows for the most time in ball possession while having the ability to save and shoot as much as possible?
In doubles, I find a good tactic is to designate positions, switching up when necessary (communication is key here).
Midfielder should stay centered, keep a well-plenished boost, and keep watch for the pass on a clear shot. Keeping the ball in play and be able to speed back to defend if needed.
Striker should be chasing the ball, taking shots, and setting up passes to the midfielder.
Goalie should be focusing primarily on the save and only clearing if able to do so without losing position.
Defender should be keeping the ball in the corners to keep the ball at a bad angle, and clearing the ball when possible.
Communicate if you are going to be Goalie or Striker. Both going for the ball can lead to an easy goal against.