Don't say a car, say a Chevy Malibu, don't say a bird, say a Robin, the harbinger of spring, don't say flower say a rose so red it reminded her of blood. Search out 'it' and replace with what 'it' is. Search out 'they' and add names or whoever 'they' refers to. Being specific is what enriches your writing, painting a picture instead of leaving a blank canvas. I notice this now in my own writing and try hard to add all the little details.
Specifics are important in all parts your writing. If people see the blue jacket with the tucked in waist and the blonde hair that hangs in ringlets, the tiny mole that rests against the outside of her right nostril, they are more likely to bond with the characters. This is especially true for series where characters move through each book, becoming more detailed as each one progresses. And it isn't just about physical details. One character may have the habit of brushing his fingers through his hair, making it stand up in tufts, or one will always add a question mark at the end of each sentence. A person may have a certain style of talking, using words not commonly spoken by others. Get to know your characters, their quirks and idiosyncrasies are what make them believable.
After finishing my last witch book I began writing the fifth Summer McCloud murder mystery, Akumal Alibi. I discovered that I'd missed the characters! And I also found that because I know them so well now they carry the story forward without little help from me. They seem to have taken on a life of their own--I see them going about their daily lives separate from me or the books. They are like real people now. I even talk to my husband about them. "You won't believe what Mrs. Browning said when Summer asked her..." Or, "do you remember that so and so lives in the Victorian now? well he's having an affair with..." I know this sounds a bit strange, but it's true. And the more you develop your characters the more this happens and the easier the story flows forward. Seriously.
If you write quickly and a plot driven narrative it's probably easier to let the story come out before going back to add all the detail. I tend to write several pages and go over them the next day before I continue forward. But once the story is done one last go through can polish it all to a high shine.
Have fun with your characters and enjoy them with all their odd little quirks. I do. Thanks for reading and keep on writing!