Part of putting together a pitch for a story means knowing who that story is for. You can narrow this down by genre, age group, and sometimes even by gender. I'd like to recommend that you get even more specific.
When I write a book, there is usually at least one real person I'm writing it for--whether or not that person ever reads it. This is a person who might have inspired the story in some way or someone I think would really like it. Here is a Storyworld Short video I made to talk more about this topic.
The imaginary readers I talked about I also blogged about on Go Teen Writers several years ago in a post titled "Who is Your Target Reader?" Here is a link to that post if you want to take a closer look.