Tips To Increase Tension and Suspense in your writing.
Do you write mysteries or thrillers? Regardless, all novels need some tension

I love to read mysteries. It’s my favorite leisure reading material. And the more suspense, the better. I wish I knew how to write in that genre, so I greatly appreciate those who do. It doesn’t seem easy to me.
How do they do it? What are the tips needed to keep the suspense building?
What I’ve read is that it takes a clock. That is the best tool used to build the blocks of suspense.
One of the most effective tools in a suspense novel is a ticking clock. If you want low-grade suspense running through your story to supplement the significant moments of tension, shorten the deadline on the main character’s mission. They must accomplish their goal sooner than planned, or something terrible will happen.
“Writing mysteries let me get away with murder. I think ‘the mystery’ may be the greatest form for social criticism, simply because it is pedestrian.” — GREGORY McDONALD.
We want our readers to feel they can’t possibly put our books down until they have solved the secret. So, how do we keep that tension going? One way to keep it interesting is to change the point of view throughout the book. It’s tricky, but it’s doable with careful planning in advance between two characters. You can also use the third-person POV. Or the omniscient through your main character. Finally, try the first-person POV or third-person limited.
Always remember to end a chapter with a “cliffhanger.” You want your readers to keep going chapter after chapter. A rule with mystery and thriller is always to leave your protagonist hanging off a cliff at the end of the chapter. What will happen next? Who knows? Very often, thriller novels add to the suspense that way.
Character development is the key to a good mystery/thriller. As a thoroughly character-driven novel, it is these people we care about and want to see their strengths in dealing with adversity. We also don’t want them so perfect we can’t relate to them. Then they would-be superheroes, which is not what we are writing about here.
“Death is a mystery, and burial is a secret.” — STEPHEN KING.
We need to see their strengths, flaws, and weaknesses. We want to care about these people and see them finally succeed. How did they survive the various trials and challenges you created for them. Their success should not be too unbelievable or too easy. But, just enough of a challenge the reader can relate to and still feel that tension.
Your hero needs to be someone your readers care about. They will follow them everywhere in the story if they care, whether to the top of a mountain or the grocery store. They will especially care if the hero could be in danger. We need to understand their motivation to make sense to us when they venture far afield.
In addition, the antagonist should be a match, so the tension and events are equally matched. Otherwise, there is no competition.
Another way to increase the tension is by the use of subplots. This device can create a scenario between the hero and the villain in the story. You can also add a couple of additional, temporary characters to move the plot along.
Another option is a temporary sense of security. Your reader will take a breath, only to exhale the next chapter when a new obstacle comes into play. This is a great way to keep your reader on their toes.
If you have successfully created a character, your readers are invested in it; you have lots of room to take them up and down and side to side in all kinds of circumstances that they survive and maybe almost fail. Your reader is right there with you.
Congratulations.