There is no surefire way to get more coins or diamonds without paying real money, but there are a few methods that may work. One method is to purchase coins or diamonds from an online marketplace. This is the easiest and most common way to get these items, but it can be expensive.
Another method is to mine coins or diamonds. This involves using a computer to solve complex mathematical problems in order to earn coins or diamonds. However, this can be time-consuming and may not be profitable over time.