Since this book is based on this topic why not make a chapter like this.

Basically, a lot of people thing 'oh I just gotta tell someone what sucks about their art and BOOM! Creative criticism!'

You- Are the scum of this art earth.
Constructive criticism is used to help an artist improve, not feel bad for not being able to achieve what's not in their artistic capabilities.
By stating unreasonable goals and complaints towards an artist's work you:
•Sound like an asshole
•Act like your some artist wannabe who hasn't drawn before
•Act unprofessional
•Make someone feel bad for doing what they most likely love
•and
MUCH MORE!!

To correctly give creative criticism you need to not only state what you believe the artist can improve on-showing them how to do so or providing a reasonable explanation on why, but you also have to state what you believe the artist should keep in their style. Tell them what you think could have improvement and tell them what you believe makes their artwork beautiful-what you first noticed in a positive light about their piece!

Criticizing in this way not only makes you feel professional, it will actually help an artist to improve!
You can't just go to a cartoonist and tell them to draw realistically,
They'd be like "wtf do I look like????"
State things that can reasonably be achieved in THAT artists STANDARD.

That's pretty much all I have,
Hope you guys learned stuff.
Enjoy!