After starting a new story, when part of the story is somewhat fleshed out, when I have a few characters, a few important locations that will occur throughout the story, I visualize it. Not only in my head, but in pictures and drawings.
For characters I always have a picture of their faces. It may be a random person, or a fusion of several people, but I like to visualize them. It makes it easier for me to spend time with them and learn how they interact with others, what drives them, why they are the way they are. Some are based on real people, or I draw a sketch of their face, but I always have an image of some sort for all main characters.
I draw out the building plans of places that are recurring in the story like an apartment or a police precinct. This is to help me understand where the characters live and interact with others. If you write a crime story and the detective catches his colleague behaving suspiciously, it implies that he/she can see the other person from their desk. It doesn’t work if in another scene you describe he/she tucked away in a corner and discreetly drinking whisky from a flask.
I found that if I have it visually available, it allows me to be consistent, and also gives me freedom to describe the same place throughout the book instead of giving a detailed description at the beginning of the book when the police officer walks into the precinct in the morning. It can also give you more meat for your story; maybe you need that officer to switch desk because he/she can’t observe the suspicious colleague from their corner, so maybe another cop is fired from the police force and the main character is switching desk and can now observe the suspicious colleague. You can even give the fired cop a greater role and have them interact somehow in the story with the suspicious colleague, or the main character. You can communicate the tension of the story also in the description of a place, and by visualizing your characters you can give them ticks and facial expressions that may be otherwise difficult to imagine or left out completely.