What a great idea, as a fairly new teacher I find myself searching for the right cue for the right student. I can't wait to see some cue suggestions here. While teaching, I try and run through 2-3 verbal cues for the same thing. Sometimes what works for one person (a visualization) doesn't work for those who are more anatomically inclined (like me). I might say "lift the heart" and also "expand the chest toward the ceiling". I try to keep a balance of those visualization cues and body specific cues so that everyone gets what they need. Cues are more often than not specific to an individual, it depends on their background and how they interpret them. There are a couple of cues that I find work in general, most of the time:
1. "Lengthen the midline of the body running from the top of the head down the spine through the floor". For the visualization I refer to "a beam of light shining from the crown to the root" (I may have made reference to a light saber at some point ). This works to bring that spine into alignment in both seated and most standing poses. It also works to "hug to the midline" in downdog (sort of the same cue about the elbows above), planks, Chaturanga, lunges and other balancing poses.
2. "Engage the fingers/toes" or "energize the hands/draw the toes toward you" helps to keep the muscles of the arms engaged (lessens the impact on shoulders/rotator cuff) and legs (protects the knee when the hip is in turnout, and while standing engaging the quads will keep you from locking out the knee).
I also remind everyone, including myself at the beginning of any practice, "honor your body where it is today, it may be different than where you were yesterday and it will be different from where you will be tomorrow". I think we, myself included, often forget what there is nothing our practice "should" look like. I agree, deepening your practice by finding those subtle muscles is way more rewarding!