There are a great many ways to play as Taric and depending on how your team is configured and how well you know who are play with depends on how you should play him. This build is for what Taric does best, radiate. this build is a support hybrid tank. focusing on making your whole team durable.

since the way i play Taric is aggressive and trying to be there in every team fight i chose flat heath quints for early game because the early game is one of the biggest factors in the match. magic resist flats for glyphs because i want to be sustainable as a tank and Taric has great armor passively so magic resit is all he is lacking. magic pen reds for early game kills with lane partner with my stun and shatter. mana Regen seals per level because late game you dont have time to go back you have to stay in the fray at all times as a support and with all the auras you give out you change the tide of battle drastically.

tank materies for the health necessary to tank and charge in and not get focused down right away in team fights and to be able to pull when neccisary.

the way support taric should be played is by maximizing how much you are helping the team. he already gives free armor and damage and ability power built in. so by getting aura life steal and spell vamp you passively heal your team with out wasting your mana or waiting on cool down for your heal. and to make your team even more durable by getting aegis of the legion you give your team all hybrid tank status for free.
in the held with this build by just being in combat you give your whole team:
20% attack speed
30 health per 5 sec
reduces opponets armor by 20
65 ability power(including ult)
25% spellvamp
20% lifesteal
42 amor(including shatter passive)
15 magic resist
42 damage(including ult)
10 %cooldown
12 mana per 5 secs

standard spells for support cv and flash

with this build by just being in combat you give your whole team:
20% attack speed
30 health per 5 sec
reduces opponets armor by 20
65 ability power(including ult)
25% spellvamp
20% lifesteal
42 amor(including shatter passive)
15 magic resist
42 damage(including ult)
10 %cooldown
12 mana per 5 secs

which means perfect support tank roll