What An Ideal Pre-Master Should Look Like
Plenty of headroom
No dynamic loss
A few seconds of silence before the song starts and after it finishes
If the above is met and all is sounding good, your song is ready for mastering.
Peaks must not go over 0 dB - between -6 dB to -3 dB gives plenty of headroom for the mastering engineer to work on.
Avoid using limiters on the master output - the loudness of your pre-master will not determine the loudness of your final master and may affect the engineers ability to work effectively.
If your song starts the moment you hit play, you may risk losing that vital first note - this problem can easily be avoided by allowing for a few seconds of silence at the beginning and also at the end of your song.
If the above is NOT met, your pre-master may look something like this...