Cheaper tickets = higher attendance = greater possession.

Don't go too drastic, try going up and down by 1 to find a level that works.

I've noticed that I get lower attendance at matches against teams with fewer fans, so it may be worth considering dropping prices for those games.

More people are going to want to see Man U V Chelsea or Barça Real, than Man U v Cardiff or Barça v Racing Santander, in real life the big games are more expensive and the smaller ones cheaper.