Exclude all processing such as imagers, saturators, compressors, EQs, clippers
or limiters from your master bus. We can discuss leaving some of the mentioned processing.
Just make sure that your mixdown is not clipping. Anywhere between -8 dB Peak
and -1 dB Peak is good.
Keep the same sample rate used in
your project. No need for upsampling or downsampling.
The standard formats I work with are 32
or 24 Bit WAVs or AIFFs. If for any reason
you are stuck with lower resolution formats
such as 16 Bit WAVs / AIFFs or even mp3s
please don't change their bit rates and
send what you got.
Please include both artist and song names in your premaster titles.