Oftentimes this gets blown over but important to establish this before snatching - before even overhead squatting really...
Here I have Noble feel the difference between non-optimal and strong positioning. I do this by bringing the barbell back, and then forward, a little bit and tugging not very hard on the bar so that he can feel that with me not tugging very hard that he is in a compromised position. Then I position the barbell in the optimal/strong position and pull hard on the bar - it's easy for Noble to feel how strong and stable he is with very little effort - even when I'm providing 10x the tension.
So what is a strong position? A strong position is when the barbell is stacked over the bones - the bones being the wrist, the shoulder, the hips, the knees, and the ankles - so that if you were to see the athlete from the side, it would be a straight line from the barbell down the side of the body. This way the skeletal structure of the athlete is supporting the barbell.
Externally rotating the shoulders helps get the shoulder blades and the elbows in proper position. Also I have the athletes not shrug because that just makes having the bar overhead more difficult - I do what them engaging the barbell and pressing up through their lats but not shrugging.
GIve this a try - hopefully it helps you and your athletes! #getliftinggetlifted #reachyourpotential