So if you have already recorded, the next steps before sending your songs to mix are:
Edit your tracks: your tracks must be edited (for example if the drummer's performance needs tightening) before sending them to mixing. If vocal tuning is needed, we can do that here (but that's an additional service).
Clean up your tracks: remove unwanted noises, and send us the right takes. If it shouldn't be heard on the record, then you shouldn't be sending it to us without a very clear explanation of why it's been included.
If you used Virtual Instruments, bounce them to audio files.
Consolidate regions, items, clips or whatever your DAW of choice calls them, so that all files start at bar 1. That way, we'll just have to import the files and everything will be aligned perfectly in our DAW. This is the simplest way to transfer your material, even if some of the time it might mean that a guitar solo has 3 minutes of silence before it. You can use wav or aiff format.
Pro Tip: if you zip your files, all silences will be compressed to almost nothing, so you'll gain A LOT of space.
Export mono sources to mono and stereo sources to stereo. For every mono source you send as a stereo file (doubling its size and e-carbon print for nothing), a kitten dies.
Name the files using a convention that will make sense for someone who is not in your head, and keep this format consistent throughout all your songs.
We can't stress this enough: please make sure that you've included only the correct files and that nothing is missing. You should test each song by importing the files into your DAW and check that everything is present and aligned. It may sound obvious to you but trust us, it's not so obvious to most.
If you recorded to a click, export the tempo map and any time signature changes as MIDI files for each song (and MIDI only, proprietary tempo map files from Cubase or others are of no use to us), and include those files in your project. If there's just one tempo for one song and it's all 4/4 then just make a note of the tempo value.
Create one folder per song, then place any audio files you want us to use in a folder called "Audio". Please don't put files in subfolders like "Drums" or "Guitars", just name the files mindfully.
If possible, include a rough mix of each song. we might want to refer to it to figure out what's the main line, the lead instrument, where the emphasis should be, etc. If you don't have rough mixes but know what you want or what you DON'T want, make notes for us in a text file.
Of course, you can just leave all that up to our interpretation. If we're wrong, don't worry, nothing is undoable. Feel free to include an extra folder containing some songs from other bands that you like the sound of. We'll keep that vibe in mind as we mix, but we'll always stop short of making you sound like a cheap clone.
If your songs contain very complex choir parts, intricate 200+ tracks of samples, or heavily orchestrated sections, our advice (if you can) is to premix those and send us stereo stems. Put those stems in the main "Audio" folder and the original rough files in a separate folder called "Slave".
And finally, tell us which song you want us to mix first. Choose one that is representative of your music, one that sets the tone for the whole collection of songs that we'll be mixing for you.
When you're ready, compress each song individually into a zip file (trust us it will save some space) and share them with us online (WeTransfer, Google Drive, iCloud Drive or whatnot, just please try not to use Dropbox, we hate it haha...).
If your internet connection is not reliable enough, put all of those files onto an external USB flash or hard drive and send it by mail. No matter what, always keep your own copy of those files in safe places (yes, you should always have several backups in different locations). Keep in mind that we will not send your drives back.
Once we receive the files, we'll work on the first song and upload a mix to our private server. It will then be up to you to tell us what you like, what you don't like, and what we should change. Some mixes can take a few trials and errors before they'll meet your expectations (especially if you know exactly what you want), so don't be afraid to give us your honest opinion during the process.
The advantage of this unattended mixing process is that you will be able to hear the mixes in listening environments that you know well (your home studio, your car, on your buddy's hi-fi...) as many times as you need. We'll systematically work through and hone each song to perfection in turn.
We generally master our own mixes as we go so you can hear what you fans will hear during the decision process of mixing your songs (and not have to second guess what it might sound like after mastering), but if you want to have your material mastered somewhere else, we will happily provide the unmastered mixes. Exported stems (separated mixdowns of your drums, bass, guitars, etc) are possible at a small additional fee unless we have been notified before mixing.