I know some people don't like this idea but I macro all my cast time dps spells (not my instants) with my faerie's heal focused on my target's target. That way whatever I am dpsing, the faerie is healing its target. I also macro phys and aldo with the faerie heal on my mouse over so that when I am focus healing someone, so is my faerie and if I cant finish a cast due to movement, she will still heal them. It works well for me.