Most mix delays are caused by file problems, not musical disagreements. Getting the handover right is half the job.
Export consolidated stems
Every track should start at the same point, usually the very beginning of the session, so everything lines up when dragged in. Export each source as its own continuous file rather than a pile of fragments.
Settings
Use the session's original sample rate and at least 24 bit. Do not convert, do not compress to lossy formats, and do not normalise. Leave headroom on every file. If the session runs to a click or a grid, state the tempo.
Naming
Name files so they sort and read clearly: source, then detail. Kick, Snare, BassDI, BassAmp, GtrL, GtrR, LeadVox, VoxDouble, HarmHigh. Avoid track numbers only, avoid spaces if you can, and never send files named Audio 1 through Audio 40.
Processing: what to keep, what to remove
Keep processing that is part of the sound: an amp simulator, a creative effect, a vocal effect the arrangement depends on. Where possible send both the processed and the clean version. Remove master bus limiting, and remove corrective processing you are not sure about, since the engineer can do it better with more context.
Include a rough mix
The rough mix is the single most useful file you can send. It shows the intent, the balance you have in mind and the arrangement decisions you have already made, even if it sounds worse technically.
Notes and references
Write a short note covering the feeling you want, which element must lead, anything you know is a problem, and any section that changes character. Add one or two references and say specifically what you want from each, such as the drum weight in one and the vocal intimacy in another.
Practical details
- Deadline, and any fixed release date.
- Deliverables: main mix, instrumental, clean version, radio edit, stems.
- Loudness or format requirements from a distributor or platform.
- Who gives feedback, and by when.
Send it once, properly
Zip everything into one clearly named folder, upload in one go, and confirm the engineer can open it before the clock starts. Drip feeding extra files after work has started is the fastest way to lose a day.