In Manager mode, access the experience points menu. Near the top of the 
screen is an option
you can toggle if you wish to have the experience points spent 
automatically. Turn the autospend
off. Save up until you have about 40,000 experience points, or roughly a 
third of a season. Then,
go back into the menu where you spend your points. You can spend a lot more 
points in one go.
This makes it easier to decide what aspects of a player to upgrade. When you 
have 40,000
experience points, turn on the auto spend. The CPU spends the points better 
if there are more
to spend.