I first started out being told that with Fiddlesticks you need to Jungle so as to provide a lasting benefit to your team giving the team two solo lanes, I found however that as I Jungled I fell behind making my CC and Ultimate far far weaker than it should be. Considering the power of Fiddlestick's CC I decided to make a change.
I then moved on to using Fiddlesticks as a Laning champion, I found that I could keep up with the team but that my gold collection rate was massively hampered because last hitting isn't fiddlesticks's strong point.
I decided to experiment and come up with a build that was somewhere in-between, trying to get the best of both worlds, eventually I found it.
What this build aims to do is provide you with a strong Laning Fiddlesticks who can remain in lane for as long as possible whilst also giving you a Fiddlesticks that can Jungle at a moments notice.
--This provides you with decent staying power and an added bit of umph to your abilities early game, I recommend you choose a sapphire/ruby crystal if you aren't a fan of Doran's ring.
Magic Penetration works wonders on Fiddlesticks, the build uses it a lot and I recommend it, therefore try and grab an abyssal sceptre.
Rod of Ages is optional and can be swapped out for another item.
Feel free to grab a defensive item at any point, I have suggested Guardian Angel but obviously if they have a caster heavy team then Banshee's is far more effective for example.
Avoid Cooldown items, Runes/Masteries and Golem have you at maximum.
Runes and Masteries:
This build gives you maximum cool down reduction, an extra 10 magic penetration to complement your passive early game and a bit of gold to try and offset your lack of last hitting ability.
Buy your items and begin to duo lane, try and launch crows at one of their champions when they are both on top of each other this will do serious damage and force them back. Feel free to use Smite to last hit the large cannon minions, but remember to have it off cool down for level 3.
At this point you will have your first rank of drain, use it to keep your health up/last hit and avoid using it on the champions unless they have been stunned. (The range is short and you will likely die)
You will now have 2 ranks in Drain, this gives you the ability to comfortably and more importantly QUICKLY take out Golem. Head to Golem (I use Ghost for speed) and open with a Smite then Dark wind then Drain, follow it up with a second drain and end it with a dark wind. Now that you have the Golem buff return to your lane and start making them hurt.
You will have taken Dark wind and will now have two spells that will be devastating to anyone who thinks they can remove you from the lane, especially with Golem. Be liberal with your mana and use Drain to convert your limitless mana into Health as often as you need to.
You will take fear, this gives you the ability to force them off of you safely but the main purpose is to keep them in your range during you ultimate next level.
You have your ultimate, head to a bush or behind a wall then charge it and land on both opponents whilst they have about half Health, drop Fear on the most likely to run and Dark Wind on any champion with some Crowd Control. You can use Ghost to chase them if you want, be careful of ganks and turret diving but if all goes well you should have 2 kills and enough gold to buy some nice items.
From here on in you are prioritising Dark wind/Fear over drain, the choice of when to take a point in DW or when to take one in Fear is entirely situational and should depend on the number of team fights.
Use your ultimate to land in the middle of the group during team fights, I recommend Guardian Angel as an item if you don't want to die after landing in the middle of them, but a bit of common sense will do just as well. Remember to use Fear on their carry and Dark wind on their Crowd Control/casters, also casting Crowstorm from a bush or behind a wall will save you having to chase people.
Ghost, far more useful than flash especially for Fiddlesticks who can use the spell to postpone the buying of second level boots and still have the ability to catch other champs even after they have used flash to escape.
Smite, this spell is mandatory if you want to take Golem quickly or have the ability to kill dragon nice and early on, it will allow you to farm as well as steal buffs much much easier.
LMAOPROTIP: If you see them doing Baron and you can get there in time, go to the cliff edge behind Baron and ultimate down into the pit. You will get the Baron buff as well as the awesome PENTAKILL!!!! if you can pull it off you will be loved and adored.
I hope this is helpful to a lot of you, the build is not designed to be a rigorous recipe of what to do but it does give you a flavour of how Fiddlesticks can be made differently to the cookie cutter builds currently out there.