How do I make a phosphate buffer solution?

The steps needed to make a phosphate buffer are listed in numerical order below. It is important to note that this is the procedure for a phosphate buffer of 5.8 to 7.4. 

1. Prepare 800 mL of distilled water in the appropriate container
2. Add 20.214 g of Sodium Phosphate Dibasic Heptahydrate to the solution 
3. Add 3.394 g of Sodium Phosphate Monobasic Monohydrate to the solution
4. Alter the solution to the final desired pH using HCL or NaOH
5. Add additional water until the volume is 1L total