I have a post-apocalyptic novel I'm working on and I'm not sure if it's better to introduce the characters first or if it's okay to start the story during a battle scene to try and hook the reader and show a bit about the state of the world then later introduce them properly. I'm just worried that without showing the characters and their relationship to each other the reader may not care about the outcome of the battle enough to warrant starting with it. Advice?
Both options leave room enough to make them interesting. The most important aspect of starting the story is that it should instantly hook your reader. A battle, if done properly, would certainly be a good way of keeping readers interested, even if they don't know anything about the opposing sides. Starting out with your characters can also work out fine, but make sure that whatever option you go for has that interesting thing to it that keeps people wanting to read more. Should you go for a character-based start, make sure that the character is interesting enough for people to care about them even after a single chapter. If the battle is in, let's say, the 4th chapter already, but the 3 chapters leading up to them feature dull, boring characters that people can't connect to, you will lose those people before they even make it to the battle. Interesting is the key word here, regardless of your choice.
A battle scene with no context is a major turn off for a lot of people. Hooking the reader doesn't mean grabbing them with some contrived 'exciting' scene that only exists to emulate the beginning of James Bond movies, it means you should make them interested in continuing to read your book. What's the best way to do that? Introduce them to the characters they'll be sharing their head with the the next hundred thousand or so words.
If you read through this or any other writing forum, you'll find that the in media res battle scene (specifically battle scene) is used as a generic reference to an overused trope, which is another way to say cliché. There must be untold other places one can start, no? I would enjoy even after the battle, as the survivors lick their wounds or celebrate their victory (or both) and through this interaction, tell not only the fight but also introduce me to the players and the connections between them.
I prefer insight into what I'm getting into - the tone, who is the mc, and placement - setting. The trouble with a battle is it could be confusing. The setting would be changing. And the reason for the battle would have to be discussed/explained as it was going on. I like Wreybie's idea of showing the aftermath. Or you could do a backpedal - One of my favorite dystopian openings is from J.G. Ballard's High Rise - This opening sentence kicks off a paragraph which does what I like to call a kind of futurepeek and backpedal. The eating of the dog comes later in the story but it's so shocking that Ballard wants to open with that image and intrigue the reader ( who devolves so much that they'd eat a dog? ) This allows him to backpedal and show the same character three months earlier enjoying breakfast on his apartment patio. A normal scene allowing us to get to know the character. ( Lolita does pretty much the same thing ) If you want you could do a kind of backpedal - start with a shocking or a surprising paragraph - perhaps a gruesome killer during the battle or just an interesting action - then lead into normalcy with the mc going about their business before the event.
I also agree with starting with the aftermath (although I never mind starting with action) and then have your characters reminisce about their lives up to the battle and then the battle itself. Unless of course, you have some drama leading up to the battle that you could simply use to set things up. I tend to lose interest with the droll .....this is so and so she works here....this is so and so ....etc If you chose to go with the battle for a start be sure to give history/introductions in the aftermath scene.....as stated above possibly the characters are licking their wounds and history of the characters and how they made it to this point could clearly be stated.
Introducing characters is boring. Battle scenes are boring. What's important when hooking the reader is to make them wonder. Make the first few paragraphs leave more questions than answers. Be vague, but not teasing. Throw them into the middle of a scene, but don't confuse them. Say you have a guy bust into a house, ready to shoot whoever lives there. But the person inside says it's too late, and they "already did something", but he shoots them anyway. It's really short, but it's very gripping. Who were those two? What's their relationship? What was the gunner trying to prevent? It introduces the rest of the story with a series of questions that eventually get answered throughout the story. The reader gets to do exactly what they picked up the book for; To find out what it's about.
Like others have said, both have their merits. If you choose the battle scene route though make sure that you give enough character info (if there's more than like 3 characters of the same gender) that people can differentiate who's who. I've run into issues where the audience couldn't follow because I wasn't descriptive enough.
Personally, I would not start with the battle scene. I wouldn't write a battle scene anywhere close to the first chapter. Why? Because the battle scene is most likely one of the most exciting parts of the story. If you start a story with one, you will most likely bore your readers until they stumble upon another important, exciting event. Set a tone, introduce some characters. Put the battle scene somewhere further in the story. Usually, people get all kinds of nervous when they know they are soon about to fight. I think it's an opportunity to give a voice to at least some of your characters. But I don't know your story well enough as you do.
Start with the characters preparing for the battle. You can introduce your MCs, their relationships, promise a battle scene to the reader and add some mystery by not giving too much details about why they fight.
The reader needs to know the stakes in a battle and what the outcome will mean for it to be meaningful. If you can convey these things in your opening chapter, then open with a battle scene if that's what you think works best for the story. Otherwise, let us get to know the story's situation via the characters first. What doesn't work well is just a crowd of people bashing hell out of another crowd of people. This is battle taken out of context, and is very irritating to plod through. Or skim through. The idea that because a battle contains action it's automatically exciting is one of the biggest mistakes a new writer can make.