Ok, you do NOT want this in 1 macro:

/focus blahblahblah
/follow focus
/cast something

There are going to be times when you need to turn your alts independantly to follow an enemy while he jumps circles around you, and with the above macro, you will not be able to do this. Mages will eat you alive.

F1 (on all chars):
/focus Mainchar
/follow Mainchar

F2 (on all chars):
/focus Secondchar
/follow Secondchar

F3-F5 - You get the idea.

1 - /follow focus

Your damage spells will be:
/cast [target=focustarget,harm,nodead,exists] Harmfull spell

Your helpful spells will be:
/cast [target=focustarget,help,nodead,exists][target=focus,help,nodead,exists] Helpfull spell

Your array of healing spells or beneficial spells desired to target specific party members:
/cast [target=charname,nodead] Beneficial Spell like healing or healthstone or trinket

Search for "/focustarget" in the forums to see some of the original posts.

This method of targetting is idea for all classes imo, even CC classes.

If you are PvPing with Ranged classes, add this to your Main's Primary fight instigating spell macro:
/targetenemy [target=noexists][target=dead][target=noharm]
/cast [target=focustarget,harm,nodead,exists] Pew Pew

This will save you from having to hit Tab to find a target. Remember only the Main should use this.