Research your novel by reading existing successful teen literature to gauge the type of story and characters that appeal to the teen market. If you have children or nieces and nephews who read teen novels, ask them and their friends what type of novel they would like to read.
Gather ideas and inspiration by reading newspapers and watching news channels. Often, the best stories are rooted in fact. Carry your notepad and pen with you whenever possible as you never know when a good idea will present itself to you.
Split your story arc down into a beginning, middle and end. Further break down these "acts" into a series of events based upon the ideas you have collected.
Create a compelling protagonist with an interesting and exciting name. Give her an antagonist who is the antithesis of the protagonist.
Develop all of your characters by writing down individual biographies for each including a list of their favorite and least favorite things, their ambitions, their jobs and their friends and families. You don't need to include all of this information in the story, but this process allows you to make your characters (and their reactions to unfolding situations) feel as authentic as possible.
Create a problem for your protagonist and build the tension by having her fail at several attempts to overcome the problem before creating a larger crisis that will serve as the protagonist's last chance to resolve the problem.
Create a time line of the novel's key events. This can be as detailed or as high-level as you wish, but even a very basic time line can serve as a useful aid to ensuring that the events of your story unfold in the right order.
Begin writing your novel and allow your own instincts to guide you through the writing process. Don't be afraid or surprised if the story deviates from your plans and leads you down some unexpected paths. Writing can be a lonely and arduous process and learning to embrace these unforeseen twists and turns can keep the whole process alive and exciting for you.
Check through your first draft for any mechanical errors such as spelling, grammar and plot inconsistencies.
Send your manuscript to trusted peers who are willing to read it and provide you with valuable feedback.
Write a final draft of the manuscript based upon any feedback provided to you by your test readers.