This is an exercise I had to do at school once.
We had a live model posing for us for 5 minutes in our computer laboratory. We had to move our 3D model into the position the model was in and make a keyframe by the end of the 5 minutes. We then had an additionnal 5 minutes to refine the pose, then we made a second keyframe. We then had a final 5 minutes to perfect the pose. After that the model took another pose and we restarted.
This video shows all the keyframes I did within a 3 hour class.