I have had a number of first-time, indie or self-published authors submitting their books for review on my blog and Instagram — a number of them in their teens. I don't post reviews of their books on my blog — honestly, I just feel bad for them.
Don't get me wrong — there isn't anything bad about wanting be to published when you're inexperienced; it is a great goal and I don't want to discourage anyone. However, I do want people to reconsider their rush to get published — I want to encourage inexperienced writers to be patient.
I define inexperience in two ways:
in the writer's age
in the writer's years spent writing
1. The first story you write and especially the first draft you write will be terrible
Unless you've written the next Water for Elephants, chances are the novel you smash out during NaNoWriMo (National Novel Writing Month) isn't going to be in a publishable state.
Many new writers cling to the first story or universe which they created. Mostly likely, the first plot line you've created is going to be unoriginal and full of holes, especially if you created it when you were 14.
Don't be afraid to let old ideas and old drafts die and try something new.
2. Don't take the option of friends and family as gospel
For many people, the first point of call after finishing their manuscript is to get friends and family to read it. While their feedback can be encouraging, their feedback is often misguided. They may not want to offend you for fear of damaging their relationship with you, or perhaps they don't normally read books (or read books in that genre) so they don't have a frame of reference to which they critique your work.
Realise that, while well-intentioned, the feedback of those who are trying to be nice to you won't help you improve.
3. Realise the permanence of publishing
Once something is in the public domain, it is there forever. This is problematic if the author "peaks" too soon, or if they write about values which they no longer ascribe to.
Look at Stephanie Meyer's Twilight series. Twilight was Meyer's first work — while it made her a stack of money and turned her into a household name, the books were not well-written. Stephen King once said:
"The real difference is that [JK Rowling] is a terrific writer and Stephenie Meyer can't write worth a darn. She's not very good."
Later, Meyer would come out with a Twilight reimagined book, and The Host — both considerably better written than Twilight. But these books were not the success which her previous books were — people had pegged Meyer as a bad writer, and new readers had little interest in reading her latest books.
In his writing lectures, Brandon Sanderson pointed out that most writers will spend 10 years working towards traditional publication before they have any real chance at being published.
4. Get real world and life experience
It's well-worth younger people sitting back and waiting before they write their magnum opus. They should go see the world, go live outside their parent's house, get their first full-time job, fall in love and vote in their first election.
A good writer has interesting perspectives because they've experienced the ups and downs of life; they write interesting characters because they've met interesting people in real life.
Younger writers, especially those in their teens, simply do not have the life experience when compared to that of someone older. There are notable exceptions; but I'm addressing the majority of young people.
I cringe every time I think about what I thought about the world when I was 16 — I was so naive. Now that I'm older, I'm really glad for the life experience that I have; I think it gives me more to say about the world, simply because I've experienced more of the world. I'm also more aware of the realities of the world; I can seen the world, and people, as complex beings, rather than thinking along black and white, stereotypical lines.
Wait until your older before seeking publication; let life experience unfold naturally for you and let this experience colour and inform your work.
5. Learn how to express yourself on paper
You may have had plenty of life experience, but an inexperienced writer may run into the problem that they don't know how to express their experience.
E.L. James ran into their problem with 50 Shades of Grey; there was massive backlash over the misogynistic messages in the books. Rather than recant her published work, E.L. James said:
"I don’t know what all the fuss is about. . . . It’s an entertaining story. A fantasy. A love story for women and that’s it."
While it is unfortunate that E.L. James won't take back the cultural damage her books created, inexperienced writers can learn from her mistakes; it's not just about learning what you want to say, it's about learning how to say it. E.L. James wanted to write a love story, instead, we got 50 Shades of Grey.
Writers should get plenty of people to read and critique their work, asking them what they thought was the main message in the book. If the message was something different than what you intended, you'll need to reconsider where your writing is leading people astray.
6. Read more books
A good writer is a well-read reader. Don't even bother writing a novel if you haven't read extensively, and are not currently reading, in that genre. If you don't read other people's books, why should you expect others to read your book?
Read, read, read!