In each world I studied, unique customs and mores had been developed to help the particular civilization through the process. But these customs varied greatly because the actual processes of dying varied greatly. Let me illustrate. Here is a picture of my crew on a small planet near the edge of the galaxy we know as 4U2C. Notice that they are surrounded by several lifelike statues in various poses. These are not carved statues but actually the final state of bodies on this planet.
Natural death is immediate, almost instantaneous, with no warning given at all.
The body is frozen forever in whatever position it finds itself in at the moment of its demise. This results in some unusual poses, to say the least. As you see, some appear to be running, some gesturing with their hands, some well, shall we say, performing various alien bodily functions. The bodies are carried to a designated area and set on the little white pedestals you see. Over time, because of the harsh elements of the planet, they all develop a certain metallic appearance.