It has to introduce your main character. You don't have to go into details, but you need enough to show if the MC is male or female, old or young, and ideally, give an idea of their personality. The opening has to show, or at least hint at, the inciting incident, the problem that starts the story for the MC. Most important, your opening has to grab the reader. Very few people have the patience to wade through pages of description before the action starts. Work on the first paragraph, and particularly the first line, until no-one can resist reading on. So, a few ways to get it wrong. Fuck the main character! This too is just for narcissist nincompoops who can't read about anything but themselves.

Have you ever watched American Idol or X factor at the audition stage? Then you'll know the way you can usually tell within five notes if the singer is actually able to sing and is likely to go through. It's the same with writing. Any writer who can't manage a decent opening is not likely to get much better a hundred pages on. Whining for a second chance because "I sing a lot better in the second verse" (or "The second chapter is really good") doesn't fool anyone. What an idiot. There are lots of books that start out slow but grow on you. But fuck you, you're just such an idiot that hardly has the patience to spell laboriously through the title. Right into the garbage can from the Amazon box if the cover does not please. Your kind had better just watch Netflix or HBO, or reruns of American Idiots and X Position.