A great beginning

The start of your story has to answer several questions very quickly.

One framework I use with my creative writing students is Rudyard Kipling's 'six honest serving men' - what, why, when, how, where, and who.

What  - the event that starts off your story.  You have to 'hook' the reader in immediately, and show them the problem/challenge your character needs to overcome.

Why - is the reason the character is getting involved in the adventure, their motivation.

When - does your story start - date, season, time of day.  Start as close to the change point in your character's life as you can.  

How - will your characters overcome their challenges?  Your character needs to be making a plan for this at the start of your story.  If you have a strange event happening, you need to explain a little about how it came about.

Where - is the setting of your story, both physically and in time.

Who - is the main character of your story.  Try to introduce him/her first, and put the nature of his/ her problem/challenge up front.

Using this framework helps you to get the story working quickly and effectively.