Being awesome at drawing just takes practice! In your spare time practice drawing / rendering using the worksheets provided. 

There are soooooooo many tutorials available on YouTube below are some of the best! 

Basics of drawing

Basic Rendering

Some videos - are done with marker pens - these are a 'nice to have'. There are several different types available 

http://www.hobbycraft.co.uk/brand/copic

search Copic markers on amazon

Designing Products