Just echoing what the others have said:
Get might to above 2k - this will help push your outgoing healing to a base of 45% or so, allowing you to add additional tactical mastery and might to push it even higher.
Getting Crit to a Tactical Crit rating of 20% will help with the heals, because we do so many HoTs, and each HoT tick has a chance to crit. I much prefer Renewed Voice + Expert Attacks as the two non-HoH traits when I do heal, helps a fair amount.
And getting a dedicated healing emblem is crucial.
Gearwise, Draigoch gear works really well for a HoH build, so while some of the Menestaid set is nice, it's not really required.
Maley Oakensage, Captain of Elendilmir
Alas Elendilmir, may you *jingle jangle* forever in the Forgotten West