Know the watch you are wearing.
Casio’s precautions separate water-resistance categories by suitable activities. They also distinguish diving watches from general water-resistant models. A number on the case is not a substitute for the instructions for that particular watch.
Check the model or module number, find its manual and read the activity guidance. Use that information before taking it into water.
Controls and condition matter.
Casio’s module 3586 precautions warn against operating controls underwater or while the watch is wet, except where the applicable instructions specifically allow it. They also explain that water resistance can be affected by aging seals and wear.
Soap, hot water and a sauna are different conditions from a controlled water-resistance test. Follow the manufacturer’s precautions rather than treating the printed rating as permission for every situation.
Make the manual part of the collection.
Keep a link to each watch’s instructions with its reference number. It takes less time than hunting for the right manual when you need to set it, charge it or understand a warning.
That habit is especially useful with pre-owned pieces, where you may not know the seal or service history. The most useful collector knowledge is often the quiet, practical kind.
Read the source.
Manufacturer instructions for the examples in this note. Always use the manual for your exact watch.

