This is how i play the League of Legends champion Fiddlesticks, I've been using this build for quite some time, and this never fails when i play mid. A lot of the matches i play Fiddlesticks mid is usual a victory, I want to share to you boys and girls if you wonder on a build you want to follow.

This Build is build on to do as much damage as possible and be a threat the whole game. even though if it last over 50+ minutes.

Pros:

A life drain, do lots of damage while get your own health back
Very good ganking champion
Good Crowd Control
Very easy champion to play
His passive that gives enemy champions - 10 Magic Resist

Cons:

Very slow hero without boots
low health (but then again, Lifestealing)
Can't to much if focused in teamfights

As summuoner Spells i use Exhaust and Flash.

Exhaust Are used when I'm using drain, so that the enemy needs to use flash or try to run away at early game. for this use its because of magic penetration and AP runes. i will do a lot of damage to them at early game but also later in the match

Flash It's probably used as many other summoners does. To get away from ganking, low health, to finish someone or use flash then fear to get a kill with teammates. You should always have flash as one of your summoner spells

One thing i usually do with Flash is to use it after I'm done cast the Ultimate. For an example, I'm standing in the bushes and casting Crowstorm, after channeling, if i did not reach the enemy champion, ill use flash, then Fear, Dark Wind and Drain in this order.

An alternative summoner spell instead of Exhaust would be Teleport. The teleport is then mostly used when to low on health, needs to shop, after killing a enemy champion early game or gank a line without loosing to much time our Lane or time running to BOT or TOP lane.

Ignite could also be used as alternative instead of exhaust but i rarely use it. only if someone else on our team have exhaust and our team is missing ignite as summoner spell. very good to use when enemy champion are fleeing from you or another lifestealer such as Vladimir and Warwick for an example.

For Masteries i try to focus on Utility with cooldowns, mana regen, Experience bonus and less death time.
But also 9 points on Offense to get some more AP, more cooldownd and more Magic. Penetration.

This allows me to lesser time to wait for skills, not so important to get the blue buff if others on the team needs it more, and do a lot of damage early game with a little bit more Magic Vamp.

As you see, i always start with Dark Wind at LVL. 1
The reason for this is mainly for the silence it got and it jumps up to 5 enemies.
You can easily kill a champion with the only use of Dark wind at early game.

Dark Wind is the Skill with the longest range so its possible to harass with it, as long get Creep Score with it.

At LVL. 2 i learn the skill Drain, if the enemy champion comes closer, then i use drain, then he will 2 options. 1: get away so that the skill ends. 2: attack me but also loose health since I'm a Life Drainer.

The main skill for Fiddlesticks in Drain thats why im maxing it first, then Fear.
Dark Wind do as much silecing at lvl 1 as it would do at skill lvl 5 thats why always max it last.

Crowstorm: Fiddle ultimate, with a lot of AP and Mag Pen, you do A LOT of Magic Damage. in a teamfight, i will use Hourglass since everybody are gonna focusing me when i just popped up ulti on them. in their frustation in teamfight, they will not see that my hourglass is on.

I always start with a Dorans, it gives me a little bit extra health, but also mana regen and 15 AP. and with my runes. i will do a lot of damage no matter what.

I usually don't go back until i have enough to afford Boots of Speed AND Blazing Wand.
If i do good at my lane, i usually buy a Needlessly Large Rod. in that way i do more damage. after thoose 2 items. you upgrade your boots for more speed and more Magic Pen.

After Deathcap, i build a Abyssal Scepter. because of the magic resist i get and it goes great with my passive skills that gives the enemy less magic resist when Me or the rest of the team attacks.

It also depends on the situation. if the AP users do low damage but the AD carry do alot. you start with Hourglass THEN abyssal Scepter. The Rylais Crystal is mostly used to get more Health but also slow the enemies when attackin. Then it will take longer for them to get away from my Drain skill.

The Farming is pretty easy, mostly last hit with auto attack or Dark Wind,
If you have low Health, you can simply Use Drain instead to go back to the Shop and recover.

I'm not very good at farming since im very busy to harass the enemy champion. but if you are good at it, you get a good Creep Score.

at Teamfights, there are two options that i always follow. And that is if its gonna be that starts the teamfight or you come in RIGHT in the middle of it.

if you are gonna start the teamfight, you better go in with Crowstorm, use fear and drain. if they are focusing you, use Hourglass. in their frustration, they will still attack you even if you are immune to all damage.

My personal favorite, is to come right in the middle of the teamfights, thats when the enemies got skills on cooldowns that could possibly destroy you. with this its not so very important to hourglass. with drain, fear, dark wind and crowstorm in a teamfight, you are pretty much OP.