Well this is common sense isnt it?
Something not common sense is this: Shamans have a Talent in their resto-tree which gives them 10% of their live back if you go under 35% hp ( it has a 50% chance to proc if you put 5 points into it - 8secs cooldown)
heals me for 1200 hp every ~10 seconds if i am und 35% hp
You can also go to the SI7 in Stormwind. There are those "Test your dps" Dummies. you can spam the attack which heals you when hitting enemys on them until you are healed to 100%.
Nothing big but it might help someone