It may seem simple and unimportant but this advice from a Mastering pro and teacher, Neil Pickles will help you along the way to becoming a great sound engineer and producer.
1. Don’t Worry About Volume, Worry About Quality
Don’t worry about volume but worry about quality. A well-arranged song, with a good mix in terms of balance and EQ, can be made as loud as any other regardless of what level it gets to the mastering engineer.
2. Check Your Balance
Balance is the relative volume differences between the different instruments. A good balance is the foundation of a great sounding mix and master! Always listen to your mixes on as many different speakers at different volumes. Always keep in mind that your hearing sensitivity changes at different volumes (Learn more about the Fletcher-Munson Curves).
3. Be Prepared
Part of the Mastering Engineers job is to make sure the songs on a CD flow in a smooth manner. When you have decided the order of songs, pre mastering can also help you spot problem differences in the balance between tracks on your LP before Mastering and correcting them.