The rider must carry their arms and hands and not lean on their own hips or rest on the horse. Correct position can be checked in any book and it is a gradual process to achieve it, keep the primary aim of keeping the hands separate from the rest of the body right from the beginner stage. The legs must not grip but cuddle the horse and the rider should think of feeling the hair of the horse and not squashing the horses insides out. When an aid is given it is an electric touch then off and try again. The difference between ask and demand is the difference between an invisible and a visible aid.
Consistency is very important.
The rider must assume the role of the teacher and gently explain what is required. No student likes to be yelled at for no reason, why should a horse be different. They cannot speak our language, you must explain what you want and they will want to continue to learn. Do not pull the horse back, feel as though you are pushing the horse under and allowing the back to bow upwards. The rider must open up and stretch tall, hips forward and in balance.