When I take my lessons with Katy, she reminds me of the usual stuff -- eyes up, hands up, shoulders back and down, thigh rolled onto the saddle, and headlights pointing forward. All terms I've heard from previous trainers or in clinics. But Katy threw me a new one at my last lesson.
I hold my head a bit forward, like many people. It may be from looking at a computer all day or reading books or walking with my head down. When riding, the goal is to ride with your body in a straight line from your ear, through your shoulder, down to your hip and out your foot. You don't want your head jutting forward like a turtle.
So, this is what Katy told me to do: Pull my head back, tuck my chin a tad, and look down at my chest. If you can see cleavage, your head is back far enough. Of course, the fact that I have no cleavage makes this exercise a bit challenging but I get the concept. And it isn't an analogy I'm likely to forget.