Correct flow/Mix to get to Mastering

How to get to the MASTER mix?
DAW: Sonar Platinum
I have my tracks recorded & EQ'd. I have routed them to their instrument group's Aux Bus (strings to string bus, brass to brass bus, piano to piano bus, etc.).
 
Pro-Channel (for each track) = Compressor, EQ, & Console Emulator (in that order).
 
I also have setup sends of my tracks to their own Aux Bus (send effects include reverb & widener) which routes to their appropriate Aux Bux (Strings, Brass, Piano, etc.). Then each instrument group's main Aux Bus routes to the MASTER bus. I'm trying to get to the Mastering of my song but don't know the proper mixing steps to get there (or what effects to add to the master bus or Sends bus) or where to put them in the Master chain (which one goes fist – compressor, EQ, LPMB, widener, etc.). Any ideas, or suggested reading, would be greatly appreciated. Just don't know the correct flow to mixing after the tracks are recorded. I know this is a very complex subject, but if there are any "Rules of Thumb" or what you've found that works best, please advise. :-)
 
Ron

https://www.izotope.com/content/dam/izotope/support/help-guides/Mixing_Guide_2016.pdf
 
http://downloads.izotope.com/guides/iZotopeMasteringGuide_MasteringWithOzone.pdf
 

If you are going to put something on the master bus, put it there from the start so you mix through it.
 
Export the project as a Mix at the project sample rate and depth.
 
Put the Mix file back into your project on the Mix track and mute.  You can use solo and mute to hear any differences between your mix output and your finalized track.  Save the project with the Mix track in it so you won't lose it - your Mix stays with the project as a back up.
 
Now you can "Master" with the Mix file, either in another SONAR session or something like Sound Forge.  However, as Bat sez above, you shouldn't need to do anything drastic to the Mix at this point.  Maybe a little nip and tuck of frequencies and pumping the average volume w/ a limiter (a few dBs is all you should need).  Just as it is easer to mix a song if the sounds are properly recorded, it is easier to master a file/song if it is mixed properly.  "Fix it in the mix or mastering stage" is not an answer.