MIX: **Make sure all tracks have the same start point. A mix engineer unfamiliar with the songs cannot guess where tracks should be placed on the timeline. **Make sure whatever resolution you export in (export resolution should be same as project resolution) applies equally to all tracks. **Make sure there's no clipping and plenty of headroom in all audio files. **Make sure edits you've made in an audio file are smooth and non-obtrusive. If you've cut-and-pasted, the mix engineer should not have to smoothe out choppy cuts. **Do NOT export tracks with tons of processing. As a general rule I ask clients to export tracks without any processing. Exceptions can be made for outboard processing that is burnt onto the track, like say guitar stompboxes and such, or effects that are integral to the sound, like a time-synced delay you are 100% satisfied with. Beyond that, it's safe to assume that any dynamic, eq, spatial or time domain processing can be better executed by the mix engineer. **In extension, regarding effects: If you have a particularly good reverb, or maybe room ambience recordings, include them as separate files, never burn them onto the dry audio. **Mark all projects with BPM. **Give all files short and concise names, like ac.guitar, lead voc. "Airy-fairy analog-style digital Roland JX-emulated synth in stereo" is NOT good. **And talking about stereo: Don't split simple stereo tracks in two: If your electric piano is a stereo recording, I want ONE stereo track, not "electric piano L" and electric piano R". **Try to keep one instrument on one file. I don't need a million files for the same electric guitar in different locations of the song, like "electric guitar 1", electric guitar 2", "electric guitar middle section". One instrument, one file, is a good rule. **And in general, try to be economic with the number of tracks. If you have heavily layered rhythm guitars, for instance, I don't need each individual track. Group them together, set levels as you like them, pan them as you want them panned and then consolidate the rhythm guitars as a single stereo file. **When collecting and sending the files, do it simple. One song, one folder, clearly marked. Feel free to enclose a text document or PDF in the folder if you have basic mixing instructions. Depending on the size of the folders, feel free to zip them. When sending, use file-sending services like Wetransfer or Filemail, or drop it in Dropbox. DON'T send huge files directly by email.
MASTERING **When delivering songs for mastering, there is one rule above all: Headroom, headroom, headroom! DON'T normalize, DON'T apply any compression or limiting on the master stripe. The more headroom the mastering engineer has, the more he can retain dynamics while still making the track pop.
**As for resolution/bit depth, bounce the song in the same res/bit depth as you have been mixing it in. **Leave a few seconds of silence before/after the song - if there are noise issues, the mastering engineer can profile that noise from the start or end of the song to deal with it. **A couple of mix level issues to be aware of when delivering a mix to get mastered: Due to the intensity of transients in drum recordings, drums, especially kick and snare, can end up getting attenuated in the mastering process. In other words, they will sound lower than they did in the mix. And conversely, the more constant elements of the drum mix, like the whoosh of cymbals, can end up sounding too loud. So when preparing a pre-master mix, it is sometimes a good idea to exaggerate the transient elements of the drum mix - especially kick and snare - while pulling back the cymbals a bit. **Another level that can sometimes change when mastering, is vocals. This is a little bit hard to predict, depending on the frequency profile and dynamic nature of the vocals, but keep in mind that under certain circumstances, a lead vocal can end up sounding a bit louder after the track is mastered. **And finally, one VERY important point: Make sure you are 120% satisfied with the mix before you send it off to mastering. A professional mastering engineer will often (myself very much included) use complex chains of analog outboard equipment, and if a client comes back after a track has been mastered and says something like "oops, I decided to re-record my guitar solo" or "darn, I forgot the cowbell", that's going to give the mastering engineer (me) a bit of a headache having to reconfigure the equipment and recall settings. So please know that what you are sending is exactly how you want it. **This also includes listening through all your bounced songs before sending them to make sure there are no glitches/mistakes that have occured when bouncing.