What should a teenager do if they have a book idea?

There are far too many people that make the mistake of focusing on publication. Just start writing and focus on writing. See how long you can make the story. Ideas count for nothing by themselves, and you will always have more ideas. If you think this idea is particularly special, then shelve it and write a few more stories before you feel ready to give this one your best shot. In essence, writing as much as you can in your early years will develop the part of your brain that handles writing (just like getting on your bike every day will develop your leg muscles and stamina), and whatever you develop in your teens will never leave you when you’re older.

But don’t just write stories. Write letters to your friends. Write answers on forums. Submit short news articles to your local paper. If you want to learn to write well you need above all to develop the place where you get your ideas and where you reason – hence write broad and write a lot.