Basic Taric Guide

Red - You can use a few different ones here (magic pen = dmg) (armor = more survivability) (straight Ap = dmg) I would go with health for more survivability early game

Blue - Cooldown reduction (faster spell spam) you can also use AP for more dmg

Yellow - Armor = More lane survivability (Can also use Mp5 for sustainability)

Quint - Movement speed allows you to close gaps for stuns

The items are interchangeable depending on what your team needs

Other suggested items:

Frozen Heart
Abyssal Scepter

Tips

It's important to control the lane early and allow your ad carry to free farm. This means you have to harass the enemies while your carry farms (stun/melee/zone them as much as possible).
Make sure to counterward so your jungle can keep ganking (early oracle is great if you can live).

Early Game

Shatter/Imbue should be leveled depending on which is a greater priority, imbue if your carry is taking to much dmg. You can also melee large minions to keep your mana high when needed. When a fight is forced stun the carry and not the support to reduce damage on your carry.

Mid Game

You should at this point have an oracle and roam a bit to clear wards on the map (as well as ward their jungle to allow for team ganks)

Late Game

You are an initiator, don't be afraid to be in melee range and at all costs protect your carry.