The first sentence of your work should grab the agent's, editor's, or reader's attention as well as the one-sentence pitch for your work does.
If you don't understand the concept of "urgency," or "hook," or "attention-grabbing," read Alexandria Constantinova (formerly writing as "Sherri") Szeman's article from The Writer (reprinted in The Writer's Handbook 1997 and in The Novel Writer's Handbook) about how to get urgency into your work: "Urgency: Good Writing Needs It." By the way, urgency applies as much to non-fiction, screenplays, scripts, and poetry as it does to fiction.
Here are some examples of attention-grabbing first sentences from contemporary, published novels.
Again, your first sentence doesn't necessarily have to be extremely short, although it shouldn't be hundreds of words long either. You can use semi-colons and subordinating conjunctions to help you out with your opening sentence, but it still has to be one sentence that's intriguing and attention-grabbing. It must have urgency.
Evaluate your opening sentence. If you read only that sentence, would you want to continue reading? Be honest with yourself. Otherwise, you'll never succeed in the writing world.Ask your friends to read it. Ask strangers in the library and in bookstores to read it: ask them if they'd like to continue reading the book.
If they say "yes," but they're half-hearted about it, you need to work on the first sentence. If they say "yes" with obvious enthusiasm, you are definitely on the right track.
If they ask where they can buy your book, prepare your query and contact RockWay immediately.