Don't "grab" the reader. Earn attention by satisfying curiosity.
1. Who wants what?
2. What is stopping him from immediately getting it?
3. What's the first thing he does to try getting it?
4. Why does this first attempt fail?
By answering these questions at the top of the story, you will tell the reader who is doing the fighting and what kind of fight it's going to be, while also assuring the reader that there's going to be an actual fight.
An effective opening quickly conveys clear and specific answers to four more questions:
1. How does the trouble start?
2. Who is the trouble happening to?
3. Why is this trouble for them?
4. Where is the trouble happening?
1. Quickly introduce the trouble, or at least the threat of it, and explain it well enough that a specific plan can be made to fight it.
2. Show the protagonist acting in a characteristic way so that the reader can recognize changes and deviations as these develop.
3. Show that the trouble hurts the protagonist enough that it will prod him into action.
4. Give the setting and tag the viewpoint character(s).
These questions need not be answered in the first 1000 words, but time should not be wasted before answering them.
It is not awful to open with a peripheral event, but it should be clearly related to the main story.
* * * * *
A story is designed to answer only one question: What happens next? The best stories never explain what happened before. But if it is necessary to introduce background or back story, remember these tips:
1. Minimize the amount of background necessary to understand the story.
2. Break background up into bits and scatter it.
3. Never use flashbacks.
4. Avoid using conveniently placed asides, either in narration or dialogue.
5. Make knowledge of the back story a goal which a character is trying to reach, and which they must fight to learn.
Sources: Dwight V. Swain and David Mamet
For more: "Storytelling Catechisms"