Use a cloth to wipe the riveter clean after each use.
Storage
Some types of riveter are available with a protective case. Using this rather than storing the tool loose will save dust accumulation and possible damage and corrosion.
The riveter handles can usually be locked with a latch located on the end of one handle. Using the latch makes for easier storage of the tool and can prevent damage to the handles.
If your riveter does not come with a protective case, it can be stored in a toolbox when not in use, to prevent any damage.
Damage
Before using the riveter, visually check to see if there is any damage.
Replacement parts
Nozzles are the only replacement parts usually available for riveters. If any other vital part of the riveter is damaged then the tool will need to be replaced.