Since mixing is an artistic task, based on taste, many times it doesn´t admit to be framed into right or wrong, but sometimes there can be improvment, specially when you are focused in achieving the sound quality of another song.
Send me your song, and optionally, send me one or two references of songs you consider as target regarding sonic quality. On return, I will deliver to you:
1. List of improvments that can be made regarding arrangment, structure and recording
2. List of improvments that can be made regarding mix and mastering
3. Two spectral (RMS) diagrams commented.