I can tell you have a passion for art in you... its what I feel from your posts and from here your submission for the contest. You have a good start.

Art and design has a lot to do with practice as well. Practice sketching and I mean a lot of it. the more you do the more it becomes second nature to you when you draw. Also in the beginning try using a pencil than a pen. The reason is because a pencil you can really show thick and thins of line thickness (line weight) and light to dark lines. Knowing how to use the pencil maybe basic but its difficult to master.

Hope to see more sketches~ cheers