how about you initiate and share some of your work here?  I'm interested to see them.

Hi bro.  I'm not at professional level whatsoever, and certainly didn't have any special training.
Honestly, I just draw as a hobby on certain subjects. Learning them from books and other references.  I'm not so much of drawing nature, e.g animal, plants, or scenery.

How about you, do you draw often?

oh, by the way.....who is Billy, you referred to?

Hi bro. Practicing is good to improve drawing (or whatever sports you are taking).  And there shouldn't be a suitable to practice.  I used to carry a small "book" (actually folded A4 paper taken from office) whenever I take LRT, drawing to kill time.  Sometimes, cannot draw because of packed train during heak hours. hahaha. 

Your colouring looks very enticing and takes lots of concentration.  Once you have done colouring, you should frame it, hang it as wall deco, office deco, etc.

There are so many good video on youtube these days.  If only we have the time to watch and learn from them. 
I agree with you, about mastering the basic before taking the next level. I'm glad you love the challenges in the books. Keep doing what you love, ya.