Although iZotope is offering this from an Ozone perspective, there should be some valuable Mastering info in this guide.
 
https://www.izotope.com/en/support/support-resources/guides/ozone-5/?&utm_medium=Email&utm_source=Recording+Mag&utm_campaign=2014-06+Mastering+Guide&utm_content=Mastering+Guide&utm_term=Blast
 

This reminds me ... I've run across an online Mastering course that looks good to me.  This guy Rob, who can't be more than 30, has a nice teaching style and has made some instructional videos that are produced at a highly professional level.  There's a free "mini-course" offered within this infomercial:
 
https://www.youtube.com/watch?v=k0FpX200S1s
 
Hope this helps somebody interested in improving their skills.  Note: I have no affiliation with Rob.  My daughter would like him to be my son-in-law, though. 
 
Cheers,
Eddie
 

Don't let her marry a musician. What are you thinking?

clintmartin
Don't let her marry a musician. What are you thinking?

 
Not unless he has a really good day job. 
 
Cheers,
Eddie
 
 

Just watched the "Rob" vid.
 
Smooth talker for sure.