Building Harmonies That Support, Not Clutter
Harmonies are easy to overdo. Three-part stacks on every line sound impressive in solo, but they turn a mix into mush. The better approach is to think of harmonies as arrangement support, not vocal decoration.
Start by identifying the song's emotional peak. That might be the chorus, the bridge, or a specific line in the second verse. Put your tightest harmonies there. Leave the verses mostly solo or with a single harmony line that doubles the melody an octave below. That creates contrast so the harmony stack hits harder when it arrives.
For the actual notes, don't default to thirds. A harmony a third above the melody is predictable and can clash with the chord progression. Try a fifth above, a fourth below, or even a unison that splits into a harmony at the end of the phrase. Those unexpected intervals create tension that resolves beautifully when the harmony lands on a chord tone.
Pan your harmonies wide. Hard left and hard right. Keep the lead vocal dead center. That creates a stereo image that feels huge without sounding crowded. If you have three harmony parts, bus them to a stereo group and compress them together so they lock into one cohesive texture.