Find the line of action, draw it.
Which sounds oh so simple, but really really isn‘t and just... I mean I spent a good year or more with my 30s poses looking like sperm mostly ok? Sperm is fine if that‘s what you can draw in 30s.
Also I might not really think about proportion in a class until I‘m getting into 5 and 10 minute drawings. Too busy with other stuff.
Also also there‘s not a whole lot of deliberate thinking in the short poses except about the mechanics of slamming the idea down. Line of action. Head. Shoulder and/or hip markers. Rough in arms and legs. Scribble hands and feet. Balance curves and straights. Are negative spaces about right? Should there be a torso outline? Rough in the volume of the torso. Rough in muscle gestures that are missing, rough in major shadows. Are there clothes, accessories or background details that are missing? Do I have a gesture for hair? And at that point I‘ve gotten well into a 10 minute drawing and I probably am nowhere near done since I haven‘t done gestures for facial expression yet and the hand and foot gestures are more scribbles than anything else.
If I‘m pushing a figure sketch past class time, I‘ll usually do a proportion check on it at that point. Nothing fancy, just some simple canvas flipping, maybe a more intense check on how negative space works.