Thanks to Duelist's Dance, Fiora excels at quick trades. Use the movement speed boost from striking a Vital to escape unscathed or set up for the next one.
Grand Challenge allows Fiora to take down even the most durable opponents and then recover if successful, so do not hesitate to attack the enemy's front line.
Duelist's Dance shows you where Fiora will try to attack from, so be ready to punish her when she tries.
Be careful when casting immobilizing disables on Fiora. If her Riposte is available, she can turn their power against you.