Vocal Harmony Singing thread

My band is keen on doing vocal harmonies, and we're getting close to being "good" but still seem to need a little ironing out. Anyone got much experience of singing in a small-to-medium group? Any tips on technique or arrangement? I could put an example of what we've managed so far if it's interesting to anyone.

Abandon the principle that the highest note in a chord is the melody. Make this obvious to listeners by emphasizing mid-chord vocals.
Pass the melodic line between singers frequently; I often give the lone vocal to one voice at a time (or two opposite-gender voices in unison) but fortify it with ooohs and aaahs from the rest of the qroup backing the lead with interestingly intertwined vocals, which the lead can use as counterpoint or to weave his or her voice amongst and between. Avoid cliche backing chords, like a A major over an A in the vocal and bass. The chord changes should always be unexpected, bringing out the emotional undercurrant of the lyrics being sung to them rather than merely the actual words being spoken. Rich, distinctive arrangements are your friend ,but don't let it settle into muck by overproduction (meaning slickness, overuse of effects, aftificiality of sounds, etc.).

Unusual instrumentation is a good thing. Have the vocals pause at key points, or introduce a new, unexpected key change to highlight a key lryic. Interveave and intertwine the vocals, by, say, having the alto voice sing in baritone range for a few notes whilst your baritone sing in the higher tenor ranges before returning to their respective standard ranges.

Yeah, the sample would be way helpful. Keep up the harmonizin'....

There is some excellent advice in there for arranging choral music but I don't know how much of it is helpful for arranging vocals in an already-written song, especially if the band has a designated lead vocalist. Particularly the "avoid cliche chords" advice sounds like you are advocating rewriting the song itself unless you are just talking about inverted chord positions, which may not make sense depending on the movement in the vocal lines and the type of texture wanted for the backing vocals.