Fiora needs an early level training, or else it'll get harder for you to level up. As soon as game starts, try to level up. Around lv11+ you'll be starting to pwn people in pvp. Until you are lv11 you may want to team up with a ranged champion in order to put pressure on enemies in early game and level up quickly.

Items I choosed for fiora boosts attack, life steal, attack speed, movement speed and one of e Fiora's biggest weakness, health. In addition, frozen mallet slows down your targets, preventing them from running away. This is a very handy item during pvp. In addition you may want to add more movement and attack speed instead of bloodthirster, for example phantom dancer or so.

You may want to start any skill you want. First skill will be useful against heroes, and secon skill will be very good early levels, considering it have a passive attack boost. As for the third skill, it is good for both slaying minions or pursuing champions with low health. Or in case of emergency you may use it to run away from enemies, since it boosts movement speed. Ultimate skill is one of the best anti-champion skills in game, dealing a lot of damage in 1v1 and I would reccomend it after using first skill, so that you will get close to your enemy with wider ranged fiest skill, and then hit the enemy with ulti, slowing him down I'd you have mallet, and then pursuing them with combination of 3rd or 1st skills, depending on how much HP the target has, that is if the target is alive.