I like the steps of completely isolating your characters, introducing a major problem that you don't get to understand all at once, then the solutions to solving the problem creates a lot of "two steps forward, one step back" situations. The story that I think is a masterpiece of suspense was Ron Howards's Apollo 13. The isolation of deep space already provided a sense of unease and lack of resources, then the explosion happens. You're shown the shaking and the shuttering, but you don't know any more than the astronauts at this point. From there, there is a several minute long sequence where things become clear and they get worse and worse and worse. You learn the ship is bleeding energy, it's sensors are all fucked up, and it's leaking oxygen. The main engine is dead, and the lander's engines are not powerful enough to bring them home. That sets the scene and then they start the two steps forwards one back thing. We might be able to stop the fuel leak: but we're not landing on the moon. We'll be able to get you home, but you have to go the long way all the way around the moon. We can save the remaining power, but you have to shut everything off and we're not totally sure we can turn them all back on, you'll also have no navigation. We can keep you alive in the moon module, but it was only designed for two people for a day and a half. We're on the right trajectory for Earth, but we still haven't figured out how to get the computer back on yet... This story also demonstrates conclusively that it’s not necessarily the unknown that causes suspense. 99% of people watching the movie knew exactly how it would end, (it was a true story) it was the human drama that made it suspenseful.
I understand that English may not be your first language but I think you meant: What steps should be taken to maintain suspense and make the readers interested? I say, let the readers help solve the mystery. Don't let it be "the butler did it" at the end if the butler was barely in the story. Tell the story so that the reader is putting clues together so that he can come to the conclusion himself that the butler did it in the storytelling.
As I have recommended in the past, read “Thrill Me: Essays on Fiction” by Benjamin Percy. Also, read authors who do this well. Kristin Hannah does it masterfully in the first two thirds of The Great Alone (then she turns it into a syrupy romance novel).
I like to use a big over all question that must be answered (whoops I initially wrote answer that must be answered lol) - and sometimes that can be figured out simply by the genre you've chosen. Mystery - needs to be solved. Romance - when will they finally get together in some sort of commitment. Horror - when will the ultimate confrontation happen. Then I like to have little questions that need answering it can be simple stuff - who will the mc take to the dance? why does the orc never let the mc lead? Suspense is all about having small escalating hitches. You don't want things to be going too smoothly. Think of your mc climbing a mountain and to make it more difficult Donkey Kong's at the top throwing barrels at him. So whatever the mc wants, make it difficult to get.
Interestingly enough, I'm at a point in my story where I just revealed the major turning point, and now I'm left with the challenge of drip-feeding the reader info slowly enough to keep them interested, but not so slow they get bored. This is gonna be fun! *slams head against desk*
Yes! I know that! I just let the story stew a bit while I go back to the start and do the edit thing. It's amazing how much you can do.
To keep a reader interested, reading a book late into the night, noted agent and author on the craft of writing Donald Maass advocates for micro-tension: Here's how it works: when you create in the reader an unconscious apprehension, anxiety, worry, question or uncertainty, the reader will unconsciously seek to relieve that uneasiness. And there's only one way to do that: Read the next thing on the page. -- Donald Maas, Writing 21st Century Fiction, (2012 paperback, Writer's Digest Books) p. 130. The unifying principle of micro-tension is [usually] conflicting emotions." --Id., p. 132 It can be as simple as a slice of pie the main character desperately wants that will break their diet.
