Understand the age of the child for whom you are writing. Because taboo subjects are particularly sensitive and are likely to use word choices that may be problematic, it becomes even more important to check to make sure your word choices are appropriate for the group to which you are directing your message.
Write to your audience. Do not dumb down your story or the issues. Place your character in a believable, candid situation and allow the story to unfold as naturally as possible. Children's books are noted for their high level of specificity as children frequently pay more attention to small details than macro-type ideas.
Be concrete. Write directly and avoid veering into the safety of abstractions. Do not be afraid to get dirty. Taboo subjects are awkward and inconvenient and the child needs the author to be truthful.
Be sensitive with how much to share. Do research using some of the children's development and psychology websites and books to determine what a child is capable of understanding at the age for which you are writing. Shape your story so that you inform at the level that is appropriate.
Avoid moralizing or telling the child what to think. The objective is to present information in a way that is appealing and interesting but also allows the child to problem solve and draw their own conclusions. Avoid clichéd language.
Be objective and show both sides of the issue fairly. Children instinctively understand if a story is grossly one-sided. Stories are more effective if both sides have substance. Children's stories are often quite sophisticated and complex.
Write actively. Show, do not tell. The character in your story should encounter the taboo subject through story action; they should not be told about it.
Resolve your story in a way that the reader will find satisfying. Do not avoid the hard stuff, and do not believe that everything has to come right in the end. Life can sometimes be messy, and good stories reflect life and assist the reader in developing the skills to deal with challenges.