Moving targets

Is it necessary to write specifically for adolescents? "The author who turns them in on themselves bores them cruelly", Anatole France warns us. In adolescence, didn't I read the "classics"? Yes, but I read them in all innocence, for the history, for the characters. Tintin or Madame Bovary, it made no difference. I have therefore decided to throw myself, as I should, into the novel for adolescents, asking myself the inevitable questions one after the other: Is there a particular fashion or a material to make use of, or subjects to avoid? And how do I reach my "desired goal" without falling for the signposts of fashion?