Performance checks are at +27 if using her harp, +23 otherwise
During Daily Prep: Use Stalwart's Ring for 5 temp HP, extend Lucky Number spell if it's a low roll, otherwise re-cast for a new roll.
During Combat:
Stay within 60ft of allies for Inspire Courage, use Lingering Composition to keep it going if possible, otherwise use Inspire Courage each round.
If Focus Points remain:
Counter Performance on visual or auditory effects
Symphony of the Unfettered Heart on allies that are grabbed, immobilized, paralyzed, restrained, slowed, or stunned.
Use remaining actions for cantrips or spells as necessary or use Bon Mot or Demoralize (with Performance).
During Exploration:
Use Inspire Competence as much as possible if there's time to prep for a skill check. It's a cantrip so it can be used on everyone's checks for Performance Aid at +27 as long as there's time to use an action to set up.
Scout gives a +2 for initiative, so use that unless there's some reason to use a different activity
Some useful spells:
1st:
Liberating Command if ally is grabbed, immobilized, or restrained.
Schadenfreude if you crit fail an effect against a caster
2nd:
Blur on a martial ally
3rd:
Haste
Slow
4th:
Bloodspray Curse
Chromatic Ray