I saw this on ChoralTalk, a mailing list for choral directors. It was under the heading of Choral Platitudes, but I don't think it really falls under the definition of a platitude.
1. Always breathe in the shape of the first vowel.
2. Inhalation, regardless of the dynamic, should always be silent, low and huge.
3. Stay on the vowel as long as possible.
4. Almost all vowels are tall vowels "space between the molars" the
exception is [eh]. (Sigrid Johnson)
5. Consonants do not need muscular strength; they need air turbulence. Let the air carry the consonants.
6. Consonants do are almost always short and ahead of the beat.
7. No two consecutive notes, syllables or words should ever receive equal emphasis. The music is always going somewhere and then returning. (Robert Shaw)
8. Feel as though you are inhaling as you sing the phrase stay in the inspiratory position.
9. Think constant flow of tone, rather than just sing.
10. Sing with the most beautiful sound you can produce all the time.
11. Never think the same pitch on repeated notes always think slightly higher.
12. Long notes never sit, they either crescendo, diminuendo, or both.
13. Dynamics are not just a question of volume they are changes of intensity borne out of the breath.
14. When you sing in unison, your own voice disappears.
15. To achieve a great legato, energize the back half of the note as it moves to the next note (Edwin Fissinger)
16. When you have nothing left (spiritually, emotionally), Deep Breathe, and use the text. (Frank Almond)
17. Shed weight as you sing higher. Drop the luggage as you ascend the stairs. (Tim Salter)
18. All music must dance. (Weston Noble)
19. There is nothing more tragic in choral singing than the look of indifference.
20. The vocal folds that create speech and song are located halfway between your brain and your heart. Great singers use both. (Robert Fountain)
21. There is no such thing as a higher or lower sound wave. Sing faster, not higher.
22. Don't think flat or sharp, think in tune.
23. If "in-tune" were a dollar, you just spent about 98 cents. (Paul Nesheim)
24. Do your best, don¹t sweat the rest. (Coach Jeff Kellerman)
Source: Garrett Lathe
Sartell Choirs, MN