Mouseover macros. Every spell. They just make everything so much easier, and quicker. What they do is make it so you simply have to hover over the person you want to heal on grid (or whatever raid frames you use), and press whatever you have keybind you have that spell on.
I think the general mouseover macro looks something like this, but don't take my word for it.
/cast [target=mouseover, exists] spellname
Other then that I don't use very many. I have Divine Plea (or whatever the 25% mana back spell is) macro that on the second press cancels it, so I can continue healing at 100% if need be.
/cast Divine Plea
/cancelaura Divine Plea
Just have to make sure not to spam it.
That's all that I use really. I have plenty of other macros but they span across all characters.
I usually macro raid warning or just yells into certain spells as well.
/cast Divine Sacrifice (AKA Raid Wall)
/rw Divine Sacrifice active, 40% less damage is being taken.
Also do it with Sacrifice, Divine Plea, and some others.
I generally don't endorse macros using several abilities at once because I often find myself only wanting to use one. The Wings+DP or Trink+DP macro can save a split second, but in most fights there are often times you can just use Divine Plea when little or no damage is being taken, like heart phase on XT or in between phases on Mimiron. That may very well be because I like doing everything manually though(never used healbot, or anything like it), if I need to use wings with Divine Plea I do, etc.
Stopcasting macros I forgot to mention, and have saved my life a lot. I generally don't spam heal (press the button while it's being cast), so I actually have it macro'd into all of my heals.