The city after dark
Night streets are the most honest place to learn exposure. There is no soft daylight to hide behind. Every neon sign is either blown out or perfect, and the difference is one stop.
After rain is best. The wet pavement doubles the lights, and the reflections do half the composition for you. Bring a tripod, or find a wall to lean on. Shoot at f/2, ISO 800, and let the shutter fall where it falls.
If a night photo looks clean, you probably overexposed it. Let the shadows stay dark.
My rule for night walks: one lens, one hour, no chimping. Walk, look, shoot, and check the pictures when you get home.
Settings: 50mm, f/2, ISO 800, 1/60s.