Killer Taric builds armour and tear early for mana and shield power.

Late game, the Manamune will make you really hurt your enemies and the Frozen Heart will keep the cooldowns low! Other than those two items, this is a fairly standard Taric Build.

I take TP over flash to help mid or top, then TP back to bot early. Late game it puts me back into teamfights faster!

Always get your armour and tear first. You can't deal damage while dead!
Upgrade Tear 5-6th, so that the Manamune turns into a Muramana and you get a huge power spike
People who lane vs Taric assume that his heals and shields suck, and he deals no damage. This will prove them wrong on both accounts.
Grab a Sheen item if you want more damage mid / late game.
Thornmail is very good on Taric since he scales with armour. Always get it if you build Gauntlet.
Remember to get your passive off even on minions to lower your cooldowns!
If you're tanky enough, you won't really need tenacity. It doesn't hurt though.
Ward Dragon!
Don't be scared to roam mid to gank or help take down a turrent.
Make sure to stand in front of the ADC to soak up skillshots.
Your ult procs passive, don't forget.
Use skills and your passive to mow down turret HP bars! Dazzle that turret even if the stun doesn't hit anything.