I don’t know how everyone else does it, but I start by making sketches of whatever ideas I have on paper. Simple sketches, nothing too fancy (Because I’m not a good artist, either), to give me an idea on where to put each thing.
Then I start by placing the camera first, fixing its angle and zoom levels, then slowly making the scenery, using the camera’s POV and my own sketch to get everything right. And I improvise on the way.
Really, there isn’t a definitive guide on how to scenebuild. Don’t try making HUGE and jaw-dropping scenebuilds from day 1. Also, learn the limits of your machine. Not everyone’s PC can handle over 10 lamps without some real lag.