There are three things you absolutely must do if you intend to write novels.
The first is to actually write. Many people will say you should write every day, and I generally like that because repetitive practice does wonders and writing every day will get you to published quicker than anything else will. This holds true for sports, dance, music, art, and any other physical skill or mode of expression a person might want to develop into a career.
I’ve taught for many years now and I have had kids tell me they want to play professional ball. One of them, now in 10th grade, carried a basketball with him everywhere. Every chance he got, he was practicing. He woke up early to practice, stayed up late, and did quite well on our team. His parents got him a personal trainer (at great expense to themselves) and I honestly believe he has a shot. But he is one of at least 100 kids who’ve told me they intend to play pro ball, and he was the only one who practiced every day. Typically they tell me they want to play, but they don’t put in the 3-6 hours of practice a day that they need to become professionals.
Fortunately no writer has to put in 3-6 hours of practice a day to go professional. We’re not looking to be professionals at the age of 19. We won’t peak in our twenties and retire in our thirties with a busted knee. But it would be a good idea to do a little organized writing every day. It gets you in the habit. Some people say that if they have to write every day it turns into a chore, and this can be true for some (not for me; I get an endorphin rush every time I write). But, if you intend to go professional, writing really will be a chore. At least part-time. If you only write when it’s fun, you won’t make much money at it.
That said, I don’t write every day. I wish I could. The ADHD makes it hard and so does my job. When report cards are due I must grade first. I don’t intend to make any money off of writing for at least several more years, though. I love my day job. I’m 44. I’m hoping to be publishable by the time I’m 55, so that I can have supplemental money (note — supplemental — writing pays for shit for most people) when I retire. I’m not your average young hopeful with dollar signs in their eyes.
The second is to read.
Read everything, but especially read fiction, and especially read fiction both in your genre and of the length you want to write.* You must read, and you should read fiction for at least half an hour every day. I typically read fiction for an hour or more. You could get away with not reading as much if you’re writing for TV or movies or something, but if you intend to write something other people will read, you must read too. I’ve read a lot of works from people who don’t read, and they struggle greatly with things like how to use words to describe settings, feelings, character, action (especially fight scenes, sex scenes, etc.). They struggle with sentence formation, paragraph structure, and the like.
Reading will not only tell you a lot about what’s considered normal in your genre, but it will teach you more about the above than any craft book, lecture, YouTube video, etc. You must read. (Plus there are genre conventions that work well, visually, but don’t work at all in text, like the jump scare. That’s a staple for horror movies but doesn’t work too well in print.)
You also want to read a tremendous amount of nonfiction because you need the largest base of general knowledge you can possibly get. I loved general education classes in college and structured my GE to help me as a writer. Today I’ve read articles on the writing process, ADHD and ADHD medications, assault weapons laws, weight loss recidivism, women and professional imaging, Morton’s toe, parents who eat lunch with their kids at elementary schools, wolf packs, teaching, and the news. Part of that is my ADHD, but part of it’s also building up such a base of general knowledge that research becomes easier.
I’ve also noticed that if I write a lot without reading much fiction, I run out of words. It’s the strangest thing. I stop being able to describe things. I think of reading as taking in fuel. You better gas up before you drive to grandma’s, that sort of thing.
The third is to critique other peoples’ works. That one deserves its own article in the interest of not making these too long.
*It’s also very, very important to read outside your genre. You should be familiar with every genre’s conventions, especially since they cross over to an extraordinary degree. Many thrillers, mysteries, SF/F books, etc. have romantic subplots, just as an extraordinary number of books are actually mysteries. For example, Harry Potter and the Sorcerer’s Stone is basically a mystery packaged as a young adult fantasy novel. I know there are a number of men out there who would not be caught dead with a romance, but that’s what Kindle is for. No one can see the cover of the book you’re reading when you’re reading on a Kindle, and if your masculinity is that fragile, you can always delete it from your Kindle when you’re done. It’ll still be there for you in Amazon’s cloud.