Here's what I have, and it works when I'm playing my balance druid.
/target [target=focustarget, harm, nodead]
The Problem: I've started playing my shaman now (enhancement), the macro does the job of keeping me on the tank's target. What it doesn't do however is start auto-attacking. This leads to me sometimes standing there like a dinkus while everyone commences with the pew pew. I tried adding /startattack [harm] but all I end up doing then is attacking the nearest hostile target.
Any help will be much appreciated.