Actually, it’s more how to NOT write for teens. With apologies to Jeff Foxworthy.
Names
If you’re working on a young adult novel, and all your girl characters are named Jenny, Michelle, and Lisa, you might be pushing 40.
I read an article ages ago, and if I could remember anything else about it, I would add the link, but one . . . → Read More: How to: Write for teens. Not you.