This really is my first build, since Fiora came out I haven't really lost a whole lot of games as her and wanted to contribute a bit by sharing my own build. The majority of what I've been seeing is that most people have been suggesting leveling her E skill ASAP. While it pretty much proves to be the majority of her dps, I've found that leveling Riposte definitely ends up being a better choice. The passive leaves her with pretty much more AD than most other champs early game, and with proper timing and practice the parry is insanely good at harassing. Almost like attacking Rammus with his shield on, enough cdr will bring it back in time to maybe block half of the opponents pokes. I'll have to finish the rest a little later though.

This is only a laning build, although I've seen great potential in her being a jungler her control in a lane is really strong in my opinion. The beginning of the game will be like most AD champs, you'd want to play a little safer and just try to get a good number of cs; occasionally poking at your enemy and returning damage using Riposte.
At level 4, with lunge unlocked she can initiate and have a good chance at a kill. After that, stacking more kills and farming creeps should bring you to domination of your game.