An audio-mastering engineer cleans up recorded audio performances and finalizes the overall sound of a song or album. Mastering audio requires years of training and practice. The best way to get this training is to apprentice at a busy recording studio. Over the course of your training, try to make industry contacts that you can use as references later in your career. Once you have the skills, you can start your own online business, which will allow you to reach clients all over the world.
Choose a location for your studio that is far away from noise sources. For example, basement studios may encounter noise problems from furnaces or water heaters. Upper-level studios may require sound isolation to keep out road noise and traffic sounds.
Buy quality mastering equipment. At minimum, you will need professional-level speakers, a powerful computer, mastering software and a computer desk.
Create a website for your business. At minimum, your website should provide background info about your professional audio experience, sample audio clips to demonstrate your expertise, a way of contacting you, and a method for delivering the audio files for mastering. For audio-file delivery, make sure you clearly specify the audio formats with which you prefer to work.
Advertise for clients on music message boards such as SputnikMusic.com and StudioRecordingEngineer.com as well as internet classified sites such as Craiglist.org and Backpage.com. Your ad should include your rates and some links to past projects, if possible. At first, it may be best to offer discounted services, or even free services, in order to generate a portfolio that you can use to get more clients in the future.
Ask each client to sign a contract that clearly lays out the scope of the project. The goal here is to avoid miscommunications. For example, if a client asks you to master a recording, he or she may not realize that this does not mean you will be editing out the performance errors of the musicians.
Master audio projects with future clients in mind. Even if you start out making very little money, the audio you work on today may win you a client tomorrow, so use all your skills to make each project sound as good as you reasonably can.
Complete each job according to the specific requirements of the client. For example, some clients may ask for their master copy on a CD or DVD, while others may want it delivered to them via a specific online file-transfer service.
Keep in mind that some clients may want to pay you via credit card or online money-transfer services. At some point you will likely need an online merchant account, such as the kind Paypal.com offers.