Congrats for making through the first week of NaNoWriMo! By now, you're hopefully settling into a routine and working out your hero/heroine.
So let's talk premise.
As defined in From the Inside Out: Discover, Create and Publish the Novel for You! by Susan May Warrenn and Rachel Hauck, a premise is a 2-5 sentence "blurb" that really zeros in on the stakes, fears, dreams, theme and plot of your story. Once crafted, you can continue to refer back to your premise to help keep yourself on track.
Your premise is a paragraph with the most important aspects of your story. Even if you don't know everything that's going to happen, it's a good idea to write your premise BEFORE you get too far in your story. Like I said, it will serve as your compass while you navigate through the many layers of your novel.
So how do you do it?
Your premise needs to have your main character easily identified as well as the character's goal for the story. Basically, you have to tell the reader what your story is about. Again, you may not have all the details, but you can still write this with general ideas. You'll need to throw in the conflict and the stakes. Then, you need to include the story question.
What's a story question?
It's different than a theme. A theme is the overall idea of the story. A story question asks "what if" on a universal level. It address a "what if" that many people are asking themselves. It is a question that connects you to the reader and makes the reader want to keep reading. Think about what your book is about and what you're saying about that subject.
For example, your story may be about overcoming social norms. The story question could be something along the lines of "What if a group of teenagers where able to see past their social labels?" You can rephrase, "Can a group of socially mismatched teenagers break through their stereotypes and develop meaningful relationships with each other?" That would be the story question for the movie The Breakfast Club. Starting to get the idea?
Take time and really go through this. A good story question will captivate the audience. Once you get it, write it down and keep it somewhere you can see it while you work. Everything in your story will revolve around it.
So now you need to piece it together. Put all the elements into a paragraph. Use colorful language and have fun with it! Like I said, getting the premise down will keep you on track and help when the writer's block sets in later on. Good luck!