Let your Stereo Bus peak at a maximum of-6dBFS (preferably at-10) . Headroom is needed for mastering engineer since further processing will be applied.
Don’t insert any processing or equalizing on the stereo mix bus. NO LIMITERS, No Compressors . It is better to process the Stereo bus with the Mastering Equipment since they are of different quality and design.
Do Not Normalize while mixing before sending for Mastering. Normalizing changes the level between instruments and stereo bus level too. Normalizing can change the micro-dynamic range between each instrument or the macro dynamic range between the softest and loudest part of your music, It changes all you mix!
Export to a Lossless file after mixing before sending for Mastering. Wave is a lossless file. Some lossy formats like mp3 cut some frequencies and affects negatively the quality of the mix and the master.
Export to same format as the mixing session. If your recording or mixing session is 48KHz 24 bit, export to the same settings. Learn More
An important point in the checklist for Mastering is to Leave a gap of at least one second during mixing. Fade ins or Fade outs include digital calculation errors that end up in clicks which are not always heard.
In case you opt to send your mix on a CD, the is a must-know point in this checklist for Mastering. Burn as Data and Not Audio. Audio CDs include errors while Audio as Data does not. Learn More
Provide ISRC codes. The Mastering Engineer's responsibility is to insert ISRC Codes so that you benefit from a legitimised protect end code for each track. Learn More about ISRC codes and how to get them.