The best method to use for forecasting is one of the following as, there are 4 types of forecasting methods, and you should choose one depending on your target:
1-Moving average: If you would like along-term trend and measure the periods for ups and downs.
2-Straight line: this if you want to measure your success or progress in something.
3-Multiple linear regression: This one specially used to measure different numbers of factors one of them is a dependent variable and the 2 others are the independent variables.
4-Simple linear regression: this one used for forecasting the coming period depending on the previous period inputs.