Build and Runes
Punish her when her Lunge is on cooldown, which is her main mobility skill.
U cant have more AD than her. Items like Thormail will be extrimely efective against her, so be tanky.
Don’t let her slap you with her baguette at early levels.
When Fiora engages with low HP, don’t get baited, it means that she has her ultimate and/or her jungler is coming to help.