_ don't play with the safety valve,
_ don't unscrew the knob until all steam has gone off the coffee machine,
_ when not in use, don't leave the knob tightly screwed in,
_ don't use espresso grind coffee ...
The list could go on and on...
Some advise - though - is so OBVIOUS that it was not - until now - worth mentioning.
The following pictures, which i use in allowance with the Copyright holder (here and here), amuse me to this day...
So i have to list another rule:
When making coffee, NEVER place the Jug in a way that the bakelite handle lands between the neck of the machine and the steam-arm:
You could have problems removing the jug after the coffee has brewed.