Mastering is no playground. Of the entire production workflow, mastering is the most critical and fragile stage. It’s also the easiest to screw up. I don’t mean that to discourage you or put you off, but to warn you to be careful. Generally, there are three reasons to be careful about mastering.
Of all the production stages, mastering requires the most intense listening. It’s the most demanding of your cognitive capabilities and the most draining. You’ll probably find that you get tired faster when mastering, compared to most other production activities (such as recording or mixing).
Keeping this in mind, I suggest scheduling mastering work in the morning. This is when your ears are fresh and clear. It’s also when you have the most energy to devote to the task. If you’re mastering when tired, you’re more likely to overlook details that normally wouldn’t escape your notice.
Mastering also requires the most detailed work. You might not worry about 0.5dB when adjusting the EQ on your guitar amp, but in mastering a 0.5dB change might require very careful consideration. This is because theres no such thing as an isolated adjustment in mastering – every change to a mixdown’s tone or dynamics affects multiple instruments (and psychoacoustic aspects) of the song.
Because of this, I suggest approaching mastering in the same way a doctor approaches a patient – “First, do no harm”. Start by listening. Then listen some more. Think about what you might adjust, but keep listening. Make the adjustment, and then listen more. Also, try to keep the adjustments subtle. Mastering is not the place for dramatic processing.
No safety net
Mastering is the most critical stage of production – it’s the very last stage of processing that your song will undergo. It’s the last chance to make it sound good. Or conversely, it’s the last chance to screw it up. Once mastering is complete, that’s it. You can’t smooth over any mistakes without going back and doing it again. There’s no opportunity to fine-tune the sound any further. When you finish mastering, what you hear is what your listeners will hear.
This is why it’s so important to be careful when mastering! You must do everything you can to make the finished product the best it can be. That means taking the time to get it right. Don’t take shortcuts, don’t settle for ‘good enough’. There’s no safety net – this is where the buck stops.