Begin with:or (incase enemy have alot harrasment)2x 2x
Boots:
I normally just go for Cooldown reduction boots (More often fiddle got the ult, the better, same with all the other spells).
But if you like so go,
Continue with:

* Against tanky team, good items:

* Against high damage/nuke:

* Against cc teams,
Rush and Then continue with what the other builds say.

* Core items,

So what im thinking about the items, you must go what your team needs, but i would recommend rylai scepter almost every game. As you know, fiddlesticks is a heavy cc, with a scepter, his cc will be alot stronker as he slow them aswell 3 seconds fear and massive silence.
Other items thats good its the zhonya hourglass, you can kill anyone with this, against fed enemys too!

This is also a old youtube vid from season 2
Play Video

Okay, I never found a build that really gets me elo, so i somehow made a build my self!
Since I played fiddlesticks, i carried my self from 1350 elo to 1650, and im still goin up and up.
The reason fiddle is the best, is all thanks to the 3 sec fear. Okay, in low elo, there is always someone on your team feeding 1-2 enemy's, NOOOOO PROBLEM!
You see, enemy adc can have 8-1-2 stats on 15 mins, but what can he do in the teamfight? When a fiddle appears with his massive damage, massive fear cc and silence (prolly slowing with rylai too).
Fiddle is the best to carry elo, as all these feds will be no problem.