One of the first things that you have to determine is upon what do you want your story to focus. Is there a particular style or genre of writing you want to give here? It's a very good opening sentence. Here's a follow up question: Where are you? What is the setting of your first line? Where does it take place? Visualizing where this sentence takes place can allow you to develop your basic ideas of where this story is going because you have been able to establish where it starts.
I think that another point of thought has to be on conflict and characters. What kind of characters do you want to develop in your story? What will be the central conflict that you are going to explore? Is this personal or about someone else? Is this completely creative? These are questions that you can ask yourself to help you figure out where to go with this and how to develop a very good opening sentence into a fine story.