One of the first things I do is to create a kind of  "pivot". Normally it's just a red cylinder, roughly the size of a human figure, which I use as camera rotation center, as a scale for everything else, as a test object for shadows and light, etc. That object will stay in the scene until the last stages. If the scene has a Poser figure, the cylinder will normally be replaced by that.

The sequence of the rest depends a lot on the kind of image I want to create. The first things to do are the things that will be the focal point. If it's an image with complex terrains, that's normally among the first things to do. If it's an image where the plants are very important, that's the first thing to do. If it's a "moody" image, the atmosphere is the first thing to do. So, I concentrate on what's more important first, also to make a kind of "proof of concept". Sometimes, I have an image in my mind that I fail miserably in putting to screen, by whatever reason. So, no bother in doing anything else if the focal point is not possible to do with my current skill set. I have dozens of folders with projects that I started but that failed on the proof of concept.

For example, in my last image, "My Kingdom", the materials were the most important (the water and the sandy beach). The rest was more or less normal stuff. So, I concentrated on that first and only when I was satisfied, I moved on to do the rest. Because many times the materials depend heavily on the lighting, the atmosphere and the materials were done at the same time, in this case.