I should not give advice on this subject considering my penchant for never using chapters, at least not anymore. I used chapters in my early writings, liked it well enough and got enough experience to share everything mentioned after this but drifted into my own method which makes enough sense for me in my internal rubber room before I can get around to editing it for sane individuals. I understand I’m in the minority because most people drift towards structure. It’s the fundamental building block of everything down to individual sentences to the overall plot, all in service to help you say what you want to say in an effective and concise manner. That said, it’s difficult to convey information when it fails to grab the audience’s attention.
The most basic method of effectively starting a new chapter is moving in the opposite direction of how the last chapter ended. People don’t continue to read a story which plods on with a single overarching mood. There’s no new information to make them believe there’s something to look forward to. If our adventurers end a chapter in a jovial state having cleared their latest obstacle, they shouldn’t start the next chapter in a jovial state from having the path ahead be clear and open and everything going just dandy. This is called the rollercoaster for the continuous ups and downs the story takes cresting and bottoming out at the chapter breaks. Much like rollercoasters this isn’t meant to shoot up and down at whiplash pace but rather on banking turns. We don’t need a light switch, zig zagging change between manic happiness and bitter depression only for narrative exposition to explain how the interesting change came about. End a chapter with the loss of a dear friend but then have the most optimistic character start the next chapter trying to bring a spark of joy back to everyone’s lives. Maybe it works or maybe it’s awkward and out of place but there’s the sense things can get better and in a story that’s almost always an unspoken promise from the writer to the audience.
In Medias Res isn’t just for the start of the story. Once the characters and stakes are established you can vary up the pacing by transitioning from a calm ending to a chapter to a high stakes moment at the start of the next. It’s a big change in mood but the trick is the cause of the change can’t be something that simply occurs out of focus with lingering emotional and character development outcomes to be resolved. Say those same adventurers end a jovial chapter surpassing one obstacle and heading to a new city only to start the next chapter in the city jail being interrogated for a possible plot to usurp the governor. The audience is taken out of their comfort zone as established by the last chapter and meant to uncover the mystery of what got the characters in hot water parallel to the characters trying to resolve their own predicament. If you’re thinking ahead you could plant seeds of how they’ll be perceived in a new town, how word of them has traveled before themselves, if they’ve angered someone with the connections to get a word in with the governor, perhaps the most cautious character’s concern over the governor’s poor reputation for hospitality will be ignored against everyone else’s overwhelming happiness. This is a nice turnaround from everything progressing nicely to hitting a roadblock face first.
Another tool to help begin a chapter is clearly showing progress towards the ultimate goal. When it’s been established what a character needs to obtain the thing they want then taking a select chapter and marking off all they’ve accomplished and all they’ve gained can serve as a reminder that the end is in sight. It could be the character easily handling a low stakes task they struggled with in the beginning or admitting to a fault instead of letting it drive them into an unwanted and unproductive conflict — then have the audience posit if that character has developed enough to make the same positive decision with the ultimate set of stakes and every immediate incentive leaning on their old nature. The change in expectations recited to the audience is there’re no regular days ahead, only the end in whatever form it comes. It adds a heap of gravity to every decision from then on out. This is clearly not a method to use every chapter or even with multiple chapters in a story for the risk of turning the plot and character arc into a checklist to be completed in gradual instalments. Completed fifth stage of grief; now acquiring self-reflection part one. Just once is sufficient for most stories if warranted at all.
Posit a moral question. Enter the characters into a moral conflict pertinent to that chapter by first asking a question. Activate the reader’s brain at the outset and layout the framework as to what they and the characters will experience in the chapter. The characters can give their immediate judgements when inside their comfort zones with the expectation they’ll soon be challenged on the same question outside their comfort zones. It isolates the chapter as a single instance with a promise that will be fulfilled very soon. Though the aftereffects can linger with the characters, the plot elements are unique onto the chapter. This could be a subsect of foreshadowing as a chapter hook with the same principles easily transferable but I far more like the moral conflict on an entertainment level than a foreboding, “One of these characters will die in this chapter. Guess who, who, who…”
Switch focus characters. If your story has multiple narrative characters, or simply characters who are the focus of the third person narration, vary up the subject matter, viewpoint, location, everything by changing who the story focuses on. If your story uses this trick, or is large enough in characters and plotlines to warrant it, know it can dramatically redirect the audience’s enjoyment. When they’ve been with a single character long enough to where their charms and uniqueness are getting stale it makes sense to revamp their energy onto a different character. It’s a great tool to skip over doldrums and “back to the farm” to someone else who’s encountering something that’ll hold the audience’s interest.
Hitchcockian bomb under the table. The gist of Hitchcock’s theory is telling the audience of a threat to oblivious characters heightens the dramatic irony and tension of every action taken and not taken. In a plot driven story this can amp up the stakes in an otherwise exposition heavy chapter. As the secret agent uncovers the evil mastermind’s plan through an interrogation of his minion we’re shown the minion has a concealed weapon that requires the secret agent be in close proximity. With proper pacing the entire chapter can ride on the minion dispensing exposition as a bargaining chip to get the secret agent in closer for the coupe d’état. The secret agent gets a bit closer then drifts away to pour a drink. The secret agent walks nearby only to divert and close the blinds. At the end of the chapter the agent (and the audience) knows everything or almost everything they need to know through touch and go dialog.
I’d advise to take all these options (and the many more you have in your own toolbox) and mix them up using one here and other there as to not get too predictable. Even the widely applicable rollercoaster method need not be a dichotomy between two polar opposite moods but rather the full spectrum of happy, sad, anxious, triumphal, etc. You don’t always have to delve into literature theory and use an opening prescribed by the genre or the Hero’s Journey or to subvert the expectations. If two characters everyone likes spend a night together it’s perfectly fine for the next chapter to start on them waking up in the morning and showing how they act and if anything changed between them. It might just be what’s expected but if that’s what everyone wants to see why embattle that with your ego against being derivative? Sometimes simple is best.