My routine is pretty simple. After I glove up, and have an old pair of shoes on;
1. I top off my tanks to make sure they are full.
2.Check and make sure the release valves are in a closed position before I remove the cap.
3. Hook up the sewer hose.
4. Then open the valve to drain.
5. While draining, I check for leaks
6. Close the valve, and repeat on the second drain pipe.
7. I rinse off everything for storage.
Takes me about 20 minutes to dump 3, 37 gallon tanks, (2 connections) and I am out of the way.
If I have the water available, and the time, I will fill the tank up again, and drain it. I put my old shoes, and gloves in separate zip lock bags. Same with the hose. They all go into a plastic container with a good lid
I top off my tanks to help with removal of the contents. I found early on that by emptying less than a full tank, it had a bad effect on the sensors. That, and I did not get full removal of debris.
I check that the release valves are in the closed position before I remove the caps for the obvious reason. On more than on a few occasions I have seen folks remove the cap, while the valve was open. I am pretty sure folks sometimes forget to close these valves when done. On two other occasions as a campground host, I caught some youngsters opening these valves with the owner not knowing about it. Surprise! Surprise!