So you've got an idea for a novel.
You've been mulling it over for some time now, I can see it in your eyes. You've got a main character and secondary characters and even the annoying bastard you're going to kill off horribly in chapter 23. So before you buckle down to start writing, I ask you this:
Do you have an outline?
You know, a guide, something to go by, a map so you don't get lost in your own head because that's a messed up place, let me tell you. My head, not yours, well maybe yours too, but anyways.
Where was I? (consults outline for blog post)
See what I did there?
Anyways, outlining is a controversial thing. Some writers always do them, some never do. I think Stephen King tries not to plot his story out ever, he just sits down and writes, sees where it takes him. Chuck Wendig on the other hand does pretty in depth outlines and even uses excel to keep track of characters, conflicts, scenes, and every other wacked out thing that goes on in a novel.
So should you do one or not?
That's really a question you have to answer for yourself. I've actually done both. I've written a story without so much as a note, just sat down and started writing the first thing that came into my head. My first novel, Lineage, on the other hand, I plotted out and outlined pretty extensively. It really rests on what kind of writer you are. Some people fly by the seat of their pants through life and write the same way. Others are more careful and meticulous, especially concerning their craft. My advice is try both and see which makes you more comfortable. After you do one of each you'll most likely know exactly which you like better.
Like I mentioned above there's also a wide array of outlining. For me what works best is a basic run down of the story once I have the plot in mind. I write out who my characters are, what they want, and what's holding them back. I write the "hooks" or the twisty plot points down if I have a few in mind just to make sure I don't forget to put them in where they need to go. Usually as I write, the story becomes more solid and I start to see other nuances of the plot I hadn't thought of before. If these bits are small but important I'll jot them down. If they're major changes or ideas like an entirely new ending to the story, I let them sit and stew on the back burner until I get to their stage time.
But that's just me. You're different and that's great. Try the two different ways and see which works. Run with it and write your novel, and don't look back.