I got this great letter from a reader:
Dear Jason Henderson-
I have been very busy with high school and working had to keep my grades up so I can go to college and be come an author. Though I have been very busy with school, I am still writing stories. I have finally moved from writing short stories to a full book-- I have just started writing it. What I was wondering is do you know an agent that would take a fifteen year old author as their client. I want to prove to everyone that this is not just a phase in my life. Hope to hear from you soon.
- Kylie, a reader and writer
I'm so sorry I missed this!
I understand exactly what you're talking about as far as wanting to prove something's not a phase. To tell you the truth, I've grappled with this my whole life and I'm published multiple times.
Here's what I've learned-- what makes people know it's not a phase is that you keep working and keep trying. I wouldn't even worry about the agent now; what I'd do is look for markets for your work. Do articles for local papers, go interview people and sell the interview.
But as to books, I think it's a GREAT idea to write a book. I think you should write the whole thing, and then when it's ready, I'd use a resource like the Novel and Short Story Writer's Market to find someone to submit to.
Along the way there are some great resources for improving your book, your writing and your selling. I recommend any of the Writer's Digest books on plot, character, etc. I also love Stephen King's book On Writing-- the second half after the (great, but less necessary) memoir in the first half. You should also research queries and query letters. And on twitter, I recommend the very harsh but great hashtag #queryfail.
Kylie, I've written full time and also written at night after a day job. It doesn't matter what anybody else thinks. Carry water, chop wood. Write because you write and because you want to.
I'm so happy you wrote-- good luck!