Columbina as an off-field Sub-DPS simply requires her to use her Skill. Her Burst is used if available, but typically isn’t required every rotation. An exception to this are on Lunar-Bloom teams, which often prefer it.
Columbina is similarly simple to use as a Main DPS, as she can simply hold down her Attack button to repeatedly use her special Charged Attack so long as the team has Verdant Dew. For those looking to maximize her, however, they can be cancelled with any of her dash, Skill, or Burst as soon as the Verdant Dew is consumed for a minor damage increase. Beyond this, just cycle through teammates as needed to reapply buffs as needed, or to buy time for Verdant Dew generation.