I usually start by removing the default terrain to start my own terrain.
In atmosphere settings I bump the height by adding another zero for bluesky heighy and haze height (creates a realistic atmosphere like seen on earth, default settings have a extremely low atmosphere) I then bump haze up to 2, for better light capturing in the sky.
The sun I change from a blue hue, to a white-yellow hue as our sun Sol produces.
I usually change the bluesky color to a bit lighter tone, and the redsky decay to a bit more of a orange tone for sunsets and lighting.
Theeen, I start whatever I was intending to do in the scene.