Overall I see that you have follow the right way and that was a step to better. But some of your pages seem moving too quickly without consider why put this line and why have to draw like this so my recommends are read the instruction several times before going to the lesson, then you should do a 10-15 minute warm-up exercise at lesson 1-2 before every drawing and try to think more about the object construction and it texture details (You should spend more time to Observe and Analyze the subject rather than try to finish it without consideration). That's it so hope you take my advice advance and drawing everyday to get yourself to a higher place and try to have fun while drawing.

All the best from me, Luke