Enhancement Shaman is strong enough to deal two mobs at same time. You can just target the first one, kill him, heal yourself then kill the next one.
A little bit challengeable. But no problem, summon the Earth Elemental Totem to pull one, you handle the rest two. For any emergencies, you can summon Feral Spirit and Stoneclaw Totem.
Four or more Mobs:
Run away. Use Earthbind Totem, transform yourself to Ghost Wolf, run as fast as you can, they wouldn't be able to catch you. After escaping from combat, prepare yourself and come back to get them one by one.
Running out of mana:
Use Mana Spring Totem and Water Shield along with Shamanistic Rage, your mana will be regenerated within couple of secends.
Shaman is a strong class, for 2 or 3 persons quest, you can still solo. Buffing you first, summon Earth Elemental Totem to pull, Feral Spirit to assist attack. When you dps on mob, take control of the aggro, don't exceed Earth Elemental Totem. Then use Heroism/Bloodlust, get rid of him.