Nature's Guidance is a Shamantalent in the Restoration tree. It significantly increases the effectiveness of direct heals on targets with [Earth Shield].
Since you can only place Earth Shield on one target at a time, the talent is mainly useful for healing the group's tank. It is also valuable in PvP. Note that it only affects direct heals, meaning that it does not increase the healing done by Earth Shield, Earthliving, [Healing Rain] or the periodic healing of [Riptide].
Tips and tactics
Refreshing Earth Shield when it is down to one stack, rather than waiting for it to expire completely, will increase the "uptime" on this talent.
On raid fights where there are two tanks who take turns tanking the boss, moving your Earth Shield back and forth will significantly increase the healing you do on the tank that is currently tanking.
Patch changes
Patch 4.1.0 (2011-04-26): Improved to 6/12/18% bonus direct healing on Earth Shielded targets, up from 5/10/15%.
Patch 4.0.1 (2010-10-12): Redesigned. Now increases effectiveness of direct healing spells on targets with Earth Shield.
Patch 3.0.2 (2008-10-14): Changed to only affect healing. Changed from 30% Intellect converted into Bonus Healing to 15% Intellect converted into Healing Spell Power, which amounts to the same bonus to healing spells.
[Earth Shield].
[Healing Rain] or the periodic healing of 
[Riptide].
Patch 4.1.0 (2011-04-26): Improved to 6/12/18% bonus direct healing on Earth Shielded targets, up from 5/10/15%. 
