I like to have assist based heals.
Well, in addition to repeater region based heals, I mean.

The assist heals are pretty basic.

#show Heal Spell
<Insert Your Assist Method Here>
/cast [help][help, Target=TargetTarget] Heal Spell

You can abbreviate Target= with @, if you prefer.

Your healer will assist your active toon, be it party1, focus, or an FTL based assist.
If the active toon is targeting a friendly, the macro will fire off the heal.
If the target is not friendly, then [help] fails, so it moves to the next conditional.
That being, is the target's target friendly... which it almost always is, because the target is beating on someone on your team.