So what do you write?
A question I get all the time is, "How do you pick a genre?"
That's a challenging question to answer. Typically when authors are starting out, you lean towards the genre's you enjoy reading; but what happens if you read a little bit of everything?
Some writers begin their story with characters, they know exactly who they want to write about and build the story around them. Some authors start with a premise, a very vague idea of what the story is about, and then build characters to fit into that story. Both of these techniques will eventually reveal the genre to you. But there are those who want to know exactly who they are writing for and then generate story ideas around that age group or demographic.
None of these techniques are wrong, but my advise, if you don't know what genre you want to write in, take a look at your book shelf. If half, or more, of the books you tend to read are a Young Adult Sci-fi, you may really enjoy writing Sci-fi. If they are Non-fiction, you may lean more towards writing Non-fiction.
The age of your characters are also typically a good indicator of the genre you might be writing. If your character is 12 years or younger, you are probably writing Middle Grade or a Children's book. If your main character is 12-18, you're probably writing a Young Adult. 18-30? That's probably a New Adult, and 30+ would fall into the Adult category.
Content will also play a big role in this. If you are writing a story about a 17 year old that has adult material (graphic sex scenes, violence and the like) you may consider writing a New Adult or Adult novel instead.
Knowing what genre you are writing is going to help you in your outlining process, and give you loose perimeters to follow, but that doesn't mean that this is the most important aspect of your planning phase. Remember, there are a lot of writers out there who get all the way to signing with an agent, only to end up having their genre changed based on a professional opinion or selling factors. The most important thing is to tell the story - your story. A solid premise and well planned outline will always take priority!