1. Erza should actually wear armor...armor that protects her and not skimpy get ups with a few plates. Also, make her use of armor more abundant. Instead of. Let's watch someone break all my armor until I use a Katana and one shot. It should be her winning through her abuse of diversity.
2. Obviously kill le fan service. Not completely....but at least make the usual outfits of characters legitimately decent. A little cleavage or leg showing isn't the end of the world...but when you virtually aren't wearing pants it's stupid.
3. Introduce Kagura before the Tower of Heavan Arc. Allowing her reveal to have more presence.
4. Minerva either beats Erza in the GMG after she has to take forever knocking her around (broken leg preventing her from truly fighting), or she stays up long enough for someone to KO her from behind while she's distracted being a sadist.
5. Silver wipes FT in the final. Because they're too tired to fight.
6. More balanced or logical ends to fights. Sadly, being like Ike just doesn't cut it #IFightForMyFriends.