The trick is not to have a strong team on the first day of the season.
On the last day of the season empty your squad and keep your top 6 or 7 players, and always have 5 or 6 low level academy players in your squad as well who you never sell.
Then buy around 8 or 9 decent players on the third/fourth day of the season.
Repeat every season, no money spent, trophies won!!!!