To be good with fiora 1st you need to know tactics 2nd know what her skills do and how they work. I ussaly play with Fiora solo top and jungle, but most solo top. 1st you need to farm till you get Madred's Razors and if you can buy boots. Then you must be level 3, and this is that part where the game begins. Cast Lunge once then Burst of Speed with Riposte then if enemy is escaping use Lunge again. after this combo he should be with 1/3 hp if he does not back do this combo again if he back's, push. So this combo is main until you get level 6. Take ultimate. then use combo and when he runs near turret or he's just left with about 1/5 HP you land your ultimate and its over. In late game its more complicated. Try not to fight unless you have ultimate or you are just over feeded. You can easily start teamfights with your ulti. in late game sell Wriggle's Lantern buy phantom dancer.
Lore:

As the youngest child of the noble House Laurent, Fiora always considered herself destined for greatness. The Laurents had dominated the dueling culture of Demacia's aristocracy for centuries, and Fiora's father was regarded as one of the finest swordsmen the nation had ever seen. Inspired by his tales of glory, Fiora began training as soon as she could wield a blade and quickly showed greater talent than any of her siblings. As she grew older, her self-confidence and rigid discipline only widened the gulf of expertise between Fiora and her peers. Her fellow duelists perceived her confidence as arrogance, but none could defeat her in combat, and each victory only heightened her lofty self-esteem. Even so, Fiora never allowed herself to become complacent in her training, and she drove herself ever harder to become a worthy successor to her father's legacy.

Her devotion turned out to be misplaced. On the eve of an arranged duel, Fiora's father was caught slipping a slow paralysis poison into his opponent's drink. Following the incident, many of his past opponents came forward with their own accusations: envenomed weapons, bribery, blackmail, and more. In an instant, he had destroyed his family's honorable reputation. Fiora was outraged. Not only had her hero betrayed her ideals, but Demacia's dueling elite now doubted her own ability. She desperately wanted to wipe the stain from her family's history but, even more, she wanted the world to acknowledge her mastery. She found her solution in the one arena where she could fight the world's strongest warriors without being accused of dishonesty: the League of Legends.

“Fiora’s ego would be insufferable if it wasn’t so . . . justified.” – Jarvan IV