at the end of each season you need to sell a few players to get your % down. for example if you finish the season on 115% for example; sell 3 players (the final saturday night) and get your team under 99% so you start the season as 5 star team. sell your GK and a couple of MCs for example and replace them with very low quality ones. easy to replace once the new season starts and that will make a big difference with whom you draw in cup and ucl comps.
i've just won the quadruple back to back in 2 seasons. trust me it works.