Open with tension and suspense. Do you want to grab your readers' interest right away? The best writing lesson I ever had, told me to begin the story when things change. What better way to change things for your characters than by sticking them in a stressful situation? Leave open questions, but not eight million of them.
Okay, onto the example. Your novel, Blood is Good, Brains are Better, features a mild mannered tax accountant named Reg. There's all sorts of information to be learned about Reg, apart from his occupation, which you can come right out and "tell", although "showing" is better. We can learn about his mild mannered nature by watching him deal with some of his more aggravating clients, or seeing him shrug his shoulders when, with nothing more than a bird flip, a Biff Tannen type character cuts him off on the highway, clipping the front of Reg's eight-year-old subcompact Chevrolet. Perhaps we'll witness Reg awkwardly, but endearingly deal with women, with whom he has zero success. We might also learn he lives with his clinically insane mother in a rundown apartment in the seedier part of town. We might see how he deals with crazy mommy, refusing to put her in a home, even though she continues her habit of collecting strays, both feline and puzzled human, but is unable to discern the difference.
There's a lot about ol' Reg that sounds intriguing, and chapter one could show us all that. The problem, though, is that what you'll end with is a chapter just chock full of back-story. Sure, it'll be interesting back-story because Reg has a fascinating home life, and seedy neighborhoods sometimes promise dark and bizarre happenings. In the end, though, the reader hasn't much clue as to how blood and brains fit, and given what genre this sounds like, they'll be expecting something to happen. So far, nothing has happened.
What if the chapter began with Reg finishing a conversation with a client whose lost all her savings, and he tells her not to worry about it. Good. We like him. Now he arrives home from work to find his mom introducing him to one of her strays--a man--who she calls Mr. Skittles. Reg is obviously concerned, but he's so used to his mother's actions, he does not protest, and after all, Mr. Skittles is extremely polite, despite his strange accent and piercing eyes. After dinner, in which Mr. Skittles does not partake, mother-nutter goes to bed, leaving Reg alone with Mr. Skittles, and Reg explains how he'll never put his mother in a home. Good. We like Reg even more, but are perhaps a little concerned for him.
The mysterious Skittles, of course, turns out to be a vampire, and he bites the bejeezus out of poor Reg. Our hero staggers out of the apartment, dazed and confused, and into a bar. There, he meets some lovely women and perhaps a Biff Tannen type who all know him and make fun of him slightly because he's acting his normally awkward and shy self. Now we feel empathy for Reg because he's nice and Biff and the ladies are mean. The inner vampire is just starting to take hold, however, and he's feeling somewhat randy. Then one woman in a dark corner of the bar comes onto him. With promises of untold pleasures and maybe a spot of blood, he follows her outside and into a dark alley where a pack of zombies attack and kill him before he's gone full vampire.
Just imagine what he'll be like when he wakes up at 4am.
That right there, my friends, is starting the novel where things change. Things move rapidly, yet hopefully we care about Reg along the way. Think of the suspense you could harness in the scenes with Mr. Skittles, at the bar, and in the alley. If the chapter ends there, your readers might just flip to chapter two. And that's what you are aiming for.
