The hook to your book is all about grabbing a reader, agent or editor at the very beginning of your story and dragging them in with you, kicking and screaming, if need be, because they have to know what happens next. These six tips will help you write the best hook you can:
1. Start in the action. Because what makes things more exciting than being in the middle of an action scene that makes you want to 'be' the character.
2. Create an unusual situation. Something that is strange or weird that makes the reader wonder how the character will deal with it.
3. Build a compelling character. Show us a character who is so "something" we can resist reading more about them, so we keep turning the pages.
4. Ask a question. What if this character just stepped off the 32nd floor of her office building, or what would happen if she opened the wrong door at the wrong time? We'll want to know the answer.
5. Make trouble. For the characters, trouble is the inciting event that changes their life, makes them do something they'd never thought to do before or creates a compelling reason for them to make something happen.
6. Promise your reader a fun ride. Interest and entice them with any of the above, or all of the above, and then fulfill your promise. It'll make a great read.
Hope these help give you inspiration! I just taught a class on hooks last month, so if you want to share your first lines, let's talk about them.