Updating first post:
Main Healer
Level 75 and all the joys that came with it (colibri holocaust) are long gone and this battle archetype essentially went with it. In ancient times, six person parties containing some combination of DNC/BRDx1-2/DDx3-4 were effective merit parties where dancers were able to live the "front line main healer" dream to the fullest.
Such a setup
is technically still viable, and in fact, dancers can still be highly effective in such a party. Unfortunately, there is exactly
zero content which is currently conducive to such a setup in today's metagame.
Still, dancers can main-heal low-man groups for various random niche activities, so discussing how to perform this role is still somewhat worthwhile.
Your goals when adhering to the main-healing archetype are as follows:
Keep your TP gain rate high such that you are able to keep up waltzes faster than your group loses HP*
Upkeep haste samba (it increases your TP gain rate as well as everyone else's). As an aside, Drain Samba is a joke.
Debuff support with steps (mainly as a byproduct of generating TP)
Don't let people die (obvious) and keep off debilitating status effects
Don't die (obvious)
*If you're waltzing a lot (your party is taking a lot of damage), you'll probably want to use a Praxidikai OA2-4 or Store TP Centovente to increase your rate of TP gain at a significant offensive cost. If your party requires less attention, just use daggers that are more focused on damage. If you're constantly sitting on TP, then you're playing too defensively. Remember, the dancer class is in a perpetual balancing act. You only need to be as defensive as you have to be. Any extra defense is wasted.
You may wonder, "but if I'm main healing, shouldn't I avoid hate as much as possible, so wouldn't reducing my damage output be a good thing?" Well, that's important to a White Mage. But, Dancers can take hits. In fact, if you're main healing, a lot of times it may be BETTER if you have the enemy's attention, because it's less likely to hit you than anyone else.
Things you'll need:
You may want to consider dropping some potency from your Waltz III set for reduced enmity. Not sure how worth it it is, honestly. You're likely to end up with hate no matter how much enmity reduction you toss in there if you are curing a lot.
You may also want to invest in your weapon skill sets (well, you should have these anyway). It's not likely you'll need to waltz constantly on the sorts of groups you'll be supporting, so you might as well stab stuff when you have some free time. A lot of our weapon skills have useful additional effects anyhow, but ***, I'm starting to get into the territory of the next archetype.
Seriously though, this isn't too complicated:
Engage
Get TP
Samba
Steps, Reverse Flourish etc.
Waltz (as needed)
Weapon skill if you have the free time / TP
It's actually harder to find content on which this is a viable strategy than it is to actually execute. As a side note, Phurba is likely not worth the offensive sacrifice.
The following information is pertinent to all battle archetypes, so you should read it no matter what:
Waltz III is our most efficient waltz (still) when it comes to HP cured / second. In general, if you're doing a lot of healing in succession, you should be using Waltz III.
If you're attempting to main heal, you'd better have your Anwig Salade agumented with Waltz recast -2 or you should just go home. To be honest, you should really have this augment for DNC if you're serious about it anyway.
Anwig should be used for Waltz III and Healing Waltz. If you're using IV/V, generally you're going for something more potent and not efficiency. As a result, you get to use the +7% potency from Etoile Tiara +2 on those. (A good example of when you might use IV/V as a good choice over III is topping yourself off between Saber Dances while soloing or when your waltz demands are not particularly heavy and you want to minimize damage lost to JA delay. If you're taking damage quickly, Waltz III with recast timer augment is more likely to keep you alive as long as your TP gain rate is fast enough.
By the way, if what you're fighting uses a lot of AoE damaging moves, inflicts a lot of debilitating status (especially if AoE), or resists physical/piercing damage, you're wasting your time bringing Dancer as a main-healer (assuming it wasn't a waste of time to begin with).
The all-end-all thing to remember for this battle archetype: Dancers are not White Mages. Don't pretend you are one.