When you try to have someone in a certain pose there are two ways to go about it: Hands on or Hands off.
You could stand there and explain it to them carefully:
Move your shoulder forward – no the other one – no your left my right.
Bend your leg – the other one.
Hands in your pocket – your back pocket I am sorry.
Now turn – the other way, not so much. blah blah blah
All good intentions but incredible exhausting for you and most importantly the client.
So asking them how to pose without showing them will make you want to start drinking beers for lunch. Just wearing you out.
Here is another idea – show them – and make it fun:
If I wanted you to lean with your right shoulder agains the wall, keep your back straight, cross your arms and lift your chin – I will show you. AFTER SHOWING we can correct. Remember we take pictures and can use our body – this is not english class where you have to describe things with words:)