If you're being swamped and get prepare enough food for all the customers don't collect the money a customer leaves once you serve them, as other customers can't take up that space when there's money on the counter.

By interior decorations in order to increase tip amounts your customers will give you, get additional clients, increase the window of time for serving during which the customer will be willing to serve you, and increase the window of time during which the customer is willing to wait for a seat.

Forward the time on your phone for a year and you will earn five diamonds, and you'll get it each time you quit the game and forward the time.

Replay completed levels and aim for the maximum scores as they will bring you more coins.