This is how I play Fiddlesticks. It's probably not the most popular way, but with this build I am very tough to kill and can still do a great deal of damage.
Fiddlesticks: Nuker (Can Jungle and go mid, but is better in a side lane imo.)
Summoner Spells: Ghost(or Clarity), Flash
Masteries:9-21-0 (Crazy right? Not really...)
Starting Items: Sapphire Crystal, 2 Health Pots
BUILD:
Sorcerer Shoes
Rod of Ages
Tear of the Goddess
Rylai's Crystal Scepter
Hextech Revolver (Or Deathfire Grasp if you want)
Turn Tear of the Goddess into Archangels Staff
Zhonya's Ring
Turn Hextech Revolver into Hextech Gunblade
RUNEPAGE:
Magic Pen Reds
Health Per Level Yellows
AP Per Level Blues
Health Quints
E W Q W Q R W W Q W R Q Q E E R E E
I only level up E once and use it to last hit far away minions or to silence an opponent. My early game damage output comes mainly from fearing them then life drain. It's a much more effective and annoying ability to hurt the enemy with than Dark Wind which bounces randomly around when there are a lot of minions. (Late game, Dark Wind becomes more useful since team fights are usually plentiful and minions are rarely there to mess it up.) You have to be good at last hitting to play him this way since most Fiddles would just level up Dark Wind and use it to farm early game.