The first sentence of any story is important. It is what makes the reader want to read more. It draws him into the story and lets him know what kind of world he is about to enter.
The most effective thing the first sentence should do is set the tone of the story. If you are writing a horror story, you can create the imagery for something scary: “A black mist crept through the forest…” You can also create some action: “The warning came immediately after the monster was sighted…”
It is also important to use a particular sentence correctly. The phrase “Once Upon a Time…” is well-known in first sentences, but it can only work in the right stories. It may work with a short fairy tale, but it won’t work as well in something like a novel. You don’t want to overuse a particular phrase. That will just bore the reader. You must also remember not to overdo the first sentence. There’s little need to make it big and complex because that can bore the reader as well. It takes something simple yet effective to draw him in. Take a look in a book that you like and read the first sentence. It is usually a simple sentence (though a comma or two isn’t bad). Very rare will you see a big, complex sentence that begins a book.
It may sound difficult to write a good “first sentence” by keeping it simple yet powerful, but it is not too hard. When you write your first sentence, just read it over and ask yourself, “Does this make me want to read more?” If it does, have a friend read it. It is good to see if an outside mind is drawn into the story as well. It doesn’t take a whole lot of effort to make a good first sentence. Just remember that it should make your reader want to keep reading. It is the usher to your world.