When you watch a movie, look at a picture or read a book, the message is in your thoughts. My mind sees the images projected in relation to my experiences, what I relate to or can rationalize as possible or fantasy.
Your reader visualizes the little things. If you write, “the old man”, I see my grandfather. But your words control the character and paint the picture you want. The man’s lifelines etched deep into his soft face. His giant ears flap as he walks across the room, and sparse snow-white hair showed his years. And you can go on about his oversized clothes hanging on his feeble frame, or worn out furless slippers. His age is clear. I see your character as you see him.
It’s the little things that complete the scene. IE; you wash your car and it doesn’t look quite clean. Then you wash the wheels and, viola, you have a masterpiece. Don’t overlook adding details to eyes, hands, feet or other characteristics that make the personality come alive.
If the person is sitting in his office, describe the room. Is it paper strewn or as if no one works there? Is it a tomb or bathed in sunlight from the large picture window overlooking the bustling city far below? What kind of pictures hangs on the walls? Cheap posters or original oils. Without saying I know the person.
Every brush stroke in your story must show the reader what you see. Draw on your surroundings, your memories, and your research to make every scene jump off the pages into your reader’s mind. If never been easier than it is today. The internet lets you look at scenes to describe. Your story is set in Paris, look at 3D maps. See the streets, the houses, the businesses, the signs, plants, cobblestones or oil stained asphalt.
Writing is about looking.