You cannot fail;
The act of doing is where the success is.
You can communicate how you feel about something through the qualities you choose to present, the tools and materials you use and through the way you use them. The material you use is equally as important as the concept/object you are conveying.
Drawing is a translation: it is your way of translating and understanding something. You are not copying something, you are either problem solving or communicating. There are no rules, so you should have no fear.