Not realising both platforms (fb & t11site) could be used for different 'free from video' options - fb for kits and t11 for tokens.
Rushing with skill point allocation = all attack or all defence of all in one place dependent on wind direction.
Not knowing when to heal, rest or sell.
Didn't fully think through the meaning of Leader when bidding.
Not posting enough meaningless crap on the forum - but fixing that.

The 1 thing I did correctly and always will was to remember its a game, its entertainment, its not an investment, it won't change your life and that behind a troll team there just might be a manager that thinks "wow great result against higher level/Q, I'm perfect manager."