1. First identify the business process.
In this step you will determine what is your business process that your data warehouse represents. This process will be the source of your metrics or measurements.
2. Identify the Grain
You will determine what does one row of fact table mean. In the previous example you have decided that your grain is ‘monthly sales per location per product’.
3. Identify the Dimensions
Your dimensions should be descriptive (SQL VARCHAR or CHARACTER) as much as possible and confirm to your grain.
4. Finally Identify the facts
In this step you will identify what are your measurements (or metrics or facts). The facts should be numeric and should confirm to the grain defines in step 2.