A first sketch can help you create a masterpiece.

Think about Doodling like drawing - sketch out the basic shapes, and once you have the entire form add details to it. You can make your initial sketch as rough as you want. Once you have the finished form, Doodle over the parts you like and add whatever details you want. You can also add details after you complete your final forms or structures (or take them away with the hot tip of the pen).