This is what I do.

Paladin - tank
Mage - shoots frostbolts
Shaman - shoots lightning bolts & heals
Warlock - uses a dot macro
Priest - heals

So when I hit my dps button, warlock casts a dot, mage & shaman start casting. Hit it again, warlock casts next dot, etc. When I hit the heal button, both shaman and priest heal.