I just finished reading an advice article on developing characters. I won't mention the writer's name because I don't personally know this person and I'm sure they meant well, but the article was terribly mishandled and I will not be reading any more of this writer's work, fiction or non-fiction. I just don't have the time to waste.
The writer's first point is to create three dimensional characters instead of cardboard cutouts. Wow, there's a news flash. Surely no writer starts out to create cardboard cutouts. The question is how to avoid it. Some good advice we get is to use real people as inspiration, to create character sketches, and to let your characters talk to you. I use 1 and 3, but character sketches are a double-edged sword. They have to be organic to work. I've found that if you sketch your character in too much detail early that it actually interferes with the character's growth during the book. In other words, it can promote cardboard characters.
Later, the article writer tells us how to introduce material from our character sketches into the story. "Show, don't tell," the writer admonishes us, then proceeds to give an example from their own work where they "tell" everything. What is this, "Do as I say, not as I do" advice?
To top it all off, the entire article is written with a smug, "I'm smarter than you" attitude. I wouldn't like getting that kind of tone from Dean Koontz or Stephen King, much less someone who hasn't even published as much stuff as I have. Hey, if you're writing a tip article then keep the smugness for your bathroom mirror. The readers are not there to serve your ego. They're expecting a return on their investment of money and time.
(Note: subject-verb disagreements intended to protect the gender of the article's author.)