Mixing a song is taking a multitrack recording- this contains a recording or multiple recordings for each instrument, such as a guitar recording and a vocals recording- and condensing it into one single audio file. A mix engineer uses techniques such as level balancing, panning, and effects to make all of your recorded tracks sound good together.
When should I get my song mixed?
Mixing is the step of audio production between recording and mastering. By the time you send your song off to a mix engineer, you should have a good-sounding recording and a solid idea of what you want your song to sound like.
Why should I get my song mixed?
While your song's individual tracks may sound great, they may not sound good together. Instruments may fight against each other for space, certain tracks may be barely audible, and your song may be overall muddy and unclear. A mix engineer's job is to prevent all of these problems, in addition to adding effects and tonal qualities to make your song stand out.
Who should I hire to mix my song?
It is common practice to hire a professional mix engineer, as opposed to mixing your own song, to get the best quality mix for your song. You can find a mix engineer on a personal website, a freelance site, or an online mixing business. What's important is that you find a skilled engineer who's easy to work with.
What do I need to give my mix engineer?
All a mix engineer needs from you is multitrack recording of your song, hopefully with a few different takes for important instruments or vocals. This can be delivered as a session in your DAW(Digital Audio Workstation, like Pro Tools or Logic) or as individual recordings. This, in combination with any notes on what you want your song to sound like, is all your mix engineer needs.
For more, you can view the following blog posts (linked):