Turn the brightness all the way down, or very close to it. This doesn't lower the gamma, only makes it so that night is much more neat.

You can't see as much but instead of having everything bathed in a pale blue light, light sources light up things proper.

After that, you'll want to turn off both HUD and Radar. I found myself taking the same routes over and over when i had the radar on, and i had some super exciting chases when it was off.

Going through alleys, smashing through fences and going offroad instead of just turning around when i see a cop coming from the other side on the map.

First person is recommended, but not needed if you find the FOV too obnoxious.