The releve passe from 5th or 3rd position. From a closed position, the body doesn't need to go anywhere but up, and can land in the passe perfectly placed -- hips square, weight in center between the legs. In my experience, the biggest mistake is the student sitting too far sideways into the standing leg when doing the releve -- throws the whole thing off balance. Perfect placement must be achieved in one beat, at the moment of releve.
The student should do the releve passe, without turning, many times at the barre, many times in the center, until they achieve perfect placement at the top of the releve every time. Then arm movements can be added. The big mistake in using the arms in pirouettes is failing to separate the arms from the shoulders. If the shoulders twist in the preparation the placement will be thrown off in the releve. The arms should move independently -- open one, close both, with no twist in the shoulders.
Once the perfect releve passe from the closed position can be done consistently, it should be done with a quarter turn. The releve position, arms and all, should be perfect every time. Then move on to the half turns and full turns. The biggest arm mistake in the full turn is letting the arms drag back behind the body. That will stop the turn in its tracks and throw off the balance. The end of the turn, still on releve, should be in a perfect position, arms and all.
Then the turn can be tried in 4th position, the problem being to achieve the same perfectly placed position from there as from the closed position. The body now must go both forward and up. Inside turns are the same -- perfect placement must happen in one beat, at the moment of releve.
There, I've said my piece!