Be careful about the way you present dialects or accents. This can be jarring and distracting. Try to vary the tension and mood as the book proceeds or you risk boring your readers to death or leaving them panting and exhausted. Heavy dramatic scenes should be followed by something lighter. Dark events are well served by comic relief.
Some writers enjoy setting a gritty police story in a bucolic little town.
Others prefer the mean streets of a big city. If you are using a real locale, get it right. Whether a place is real or invented, make it resonate through details. Name and describe the locations your characters visit. Explore the experience through all of the characters' senses.