Fiddlesticks support is all about getting your ADC as fed as possible with your high early game kill pressure and decent peeling late game. Can be extremely rewarding but will be punished hard for bad positioning.

Pros:
- High early game damage
- Can kite and peel really well
- Watching a Master Yi running away at 500mph is fun

Cons:
- Damage kind of falls off late game
- No escapes
- Squishy
- Can inadvertently steal farm

Pick up some AP blues and Magic Pen reds along with flat Armor yellows to ensure you can dish out that early game damage. Toss in some Movement speed quints so you can run fast.

I generally go for TLD for when you bounce your crow between two people the proc can chunk them for half health at level 1. The rest is purely up to customization.

Early Game
Throw out your crow whenever you see the ADC is going for the CS and just totally **** on them through out laning phase. If they try to trade, one Q on the ADC will generally win you the trade. Start to roam once you hit level 6. Vision control is extremely important.

Middle Game
Once you have your Zhonyas you can Ulti enemies under tower and fear them out of the tower, while a teammate lays in wait. Ult-Flash-Zhonyas is a good way to initiate fights.

Late Game
Your damage is starting to fall off once enemies build magic resist. So play for objectives and stick with the team. When teamfighting stay near your backlines with your Q ready to fear away any prospective assassins.