Use a tripod or keep the iPhone completely still
Clean the camera lens
Turn on Night mode if available
Set exposure time to the longest option
Lower exposure if the lights are too bright
Use the rear camera
Turn off flash
Turn off Live Photo
Turn off HDR if it interferes
Use a camera app with manual controls if possible
Set ISO as low as possible while keeping the image bright enough
Focus on infinity or the farthest setting available
Shoot in RAW if supported
Use a 3-second or 10-second timer to avoid shake
Take multiple shots
Keep the phone warm to preserve battery life
Frame the sky with foreground elements if desired
Avoid bright city lights
Use airplane mode to save battery
Check and adjust white balance if using manual controls
Experiment with different exposure times and settings
Hold the phone steady until the capture finishes