Keep the collection cup and neck as clean as possible - clean both every time you empty it.
Take your pump apart and clean it internally every few months. Completely clean the unit inside and out at least twice per year.
That's about it.
To clean it out, hot tap water and a brush (that has never touched soap and is dedicated for aquarium use) is about the best thing to use.
You can soak calcium crusted pump parts, etc in vinegar or CLR to remove the calcium. If you use CLR, rinse very, very well before returning anything to service.