What regular maintenance should be carried out on the air suspension compressor?

Which compressor?

For a Hitachi I would do nothing until you get your first fault message and then rebuild it. After the first slow to fill message the compressor will keep running for quite a while and the message only comes up occasionally but does become more frequent over time. With mine I already had a rebuild kit ready to go and rebuilt it soon after the first message - only takes about an our to remove, rebuild and refit - I remove to top and bottom covers first then the top bolt is easy to remove. In Aust we do not normally have the corrosion issue on securing nuts and bolts that other countries have. 07MY RRS TDV6
Arctic Frost
Aspen Interior