there is a ton of information buried in many threads most of the good ones are captured on the wiki and stickys.

I do not like using Target=name in my macro's anymore. Well not in that manner if that person dies you need to make sure and have a backup. some folks like to use focus but I like a more focusless approach.

i have one macro in ActionButton12 on each toon that reads something similar to this.

/target [target=focus,help,nodead][target=toon1, exists,nodead,help]; [target=toon2, exists,nodead,help]
/assist

Each macro has different names so if the person ahead of them dies they take over and everyone targets them. The one below is on my third toon if the two before him dies he is the one. Notice I start off with a focus check I do this incase I want to assign focus fire or CC to my secondary toons.

Each harmful and beneficial spell looks something like this.

#showtooltip Chain Lightning
/click [noexists][dead][noharm] ActionButton12
/cast Chain Lightning

what happens if if I have a target and its not dead I will cast Chain Lightening. (hrmm I just thought of something I better add a focus=target in there for stated reasons above...) If I do not have a target or its dead than it will /click Button12 which is the assist macro above.

It seems to work very well. I got this from the wiki I am sure I have so much stuff written down I did not keep track of where I gleamed it.