1) After using broken boxes and an amplifyer that had a resistor dead from the first party I threw with 14 , finally buying a pair of decent monitors and treating my room ....after 11 years of listening to stuff totally collored and distored by my sound system (which also destroyed my sense of good taste...probably the result of the very unique sound of the 240 mixes I have done so far)....but hey, if you can hear what compressors and stuff does on a totally destroyed system, you still can't imagine what I suddenly heared in my CD collection.... :D I can't truly tell which microphone was used , but at least I can distinguish some instruments (brands, genres) and hear the settings of the compressors, reverbs, limiters and ...
( but hey, I learned how to memorize how my stuff mixed on one pair of speakers will sound on the 5 different stereo systems at my parents house, how it sounds in 3 or more car systems from friends and how it sounds in cheap lounges and clubs in my area :P )
2) Phase, Stereoimaging and overall learning about theoretical stuff in sound engineering and applying my math and economics knowledge on the way I craft mixes. ^^
3) finding gear slutz
4) instead of working on a "mix", working on a cultural product . Meaning: choosing effects not only because I like them or they produce a good sound, but because the produce the sound I am trying to have in the mix for historical reasons (from beatle guitar sound, to jay z or timbo vocal processing, to detroit drum treatment or the good old philly sound to the synthies )
5) keeping notes . notes on what I hear in mixes from various genres, notes from what I know what I should do, notes of what I did and what I want to do to a mix, and "researching" on how I mix my stuff towards a standart and balanced sound while still colouring the instruments and vocals the way I want them. (it's like choosing a right sample to fit your message and vibe, you want the right sound on each instrument to represent a memory or atmosphere that the listenor might recognize)
6) project based mixing. Not simply working with an artist to get the sound he wants, but always keeping in mind who is supposed to listen to it, who the main competitors in the genre are and how everything the artist gives me fits into his plan. And also being able to convince an artist that he is going nowhere with a specific approach to his music (most people I came to work with being non-pros and copying others mainly)
8) Stopping to listen to people that don't know anything... not about what they want, how to get it and not that sometimes one may also just comply with someone elses ideas in order to get better. Stopping to work with people that simply don't want to progress.
9) having clear guidelines for the studio. No smoking, no drinking, no pot. Etc.
10) reading about and studying the gear I use. Technical stuff, experience sheets, knowing who used it where and what for in which mix.
11) Selling UAD and T-Raks
Maybe it is worth mentioning that despite 5 days of constant working with my new avalon and 6 different vocalists working with it, I have not yet had an aha effect comparing it to my good old and heavenly cheap art and behringer preamps .... I don't get it...
So yeah, using my mind besides my ears has been an advantage both for producing and mixing (or at least when delegating mixes)