Most problems with paintings tend to come from one of two things; an error in drawing or the value relationships.
This is why the traditional French ateliers taught drawing, with students spending months, or years drawing from casts and copies before graduating to a life model.
Ateliers of the present day still follow this idea, with students spending the majority of their time drawing. Usually students work through the Charles Bargue Drawing Course, which contains around 70 plates of drawings to copy that have been created from copying casts of famous sculptures.
Last year I attended an atelier in the city for a few months; drawing and then learning a few painting techniques. I then decided to take time out to work through the plates on my own. The last plate I worked on was the arm from the statue of Moses by Leonardo. This year I’ve made a resolution to attempt to complete the course, to draw all of the plates. I have a little more than 1 per week, and some may take 20 hours or more. To that end, my goal is ambitious, but I believe it will result in my skill level taking a great leap.