Have your grease trap cleaned / pumped out / emptied / vacuumed out every 1 to 3 months.
Use strainers in the sink to prevent food going into the system.
Wipe grease out of pans before washing.
Use hot water to wash dishes to prevent build up of grease in the sink.
Don’t pour oils and fats down the sink – they solidify and may block the system and build up in the tank. Instead, put small amounts in the compost or into a container such as a milk carton to throw out with the rubbish.