OK, now you're ready to write. But where to start? The first sentence of your blurb should set up "situation normal." Where are we when the story begins? What is about to change? In Twilight, it's "Isabella Swan expects her new life in Forks to be dull." We know immediately where she is, and what she expects. We know that this is going to change - if someone expects something to be dull, we know that they are going to be surprised.

For my story The Dreamers of Dreams, the first sentence of the summary is this: "Seventeen-year-old Taylor Donadi has always dreamed of being a singer." This is situation normal for Taylor: her dream of making it as a singer. This is the case for every genre. Here are some examples of other genres, plucked from my bookshelf:

Crime: "Makedde Vanderwall has her PhD and has started a new life in Australia with her detective boyfriend, Andy Flynn." (Hit by Tara Moss)

Science Fiction: "On a remote, icy planet, the soldier known as Breq is drawing closer to completing her quest." (Ancillary Justice by Ann Leckie)

Literary fiction/General fiction: "As children, Ruth, Kathy and Tommy spend their childhood at a seemingly idyllic English boarding school." (Never Let Me Go by Kazuo Ishiguro)

Now that you've worked out what your story is about, you know where to find the hook. The hook is basically what compels the story along - what makes you keep reading, because you want to find out what happens. You have situation normal: the hook is what is about to change. The hook is what makes you keep reading.

In Twilight, it's Edward: everyone likes Bella, except this guy. Why? And will they get together?

This can be subtle, as in the case of Ishiguro: "As they grow into young adults, they find that they have to come to terms with the haunting reality that awaits them." Or it can be a direct question, which you will answer through the reading of the story. In my summary for The Dreamers of Dreams, the final sentence is this: "As fame and fortune beckons, how can Taylor stay true to herself and her friends?" The blurb for Hit concludes: "If the boy didn't kill Meaghan, then who set him up? And how far will they go to keep their guilt a secret?"