I like sketching more than drawing because I think that it is important give the final detail with paint than only with pencil, however many students think that it is more important drawing than sketching. In my opinion, learning to drawing could be boring and take more time than learning to sketch and sometimes if you want to finish your painting with colour it is not necessary to be a master drawer.
When we want to draw like experts it is important to practice every day for a minimum of twenty minutes and use the correct pencil for shadows and shines, by the way, you need to use a soft eraser and a professional stamp blending to give the final details. Another important thing it is uses a drawing paper or a sketch book to have a record of your progress. If you have a problem with your drawing I will help you every Wednesday but you must remember that once a week it is not enough. You have to practice every day.