What type of ear does it take to be able to do your own mastering?
Can it be achieved if you practice enough and treat it like a mixing process?
I've experimenting with this process for just about six years and have done a variety of techniques from mastering to not having mastering at all.
I'll say that my ability to understand each tool and listen more carefully came with an upgrade to my speakers. That precision lead me to be more precise in my headphone listening ability.
Basically, my mix was what helped me get the results I was after, but i am still unsure about how to go about self mastering.
I am completely ok strapping on a compressor and a limiter and calling it a day, but i tend to spend a few weeks getting that compressor and limiter to sit right, while getting the loudness of the track to be not so over bearing.
I don't use any thing else outside of that because I don't think my music calls for it. But the end result seems to have a more pleasurable listening experience when ever i compare my tracks to other people. My comparisons are often way to loud lol.
to be honest in this day and age due to the loudness war and 'in the box' mastering you can very much get by with having a tight mix down and then just using mastering to boost your average volume up to a more commercial level. So in essence you are raising the volume of a well mixed track. nowadays that can give a competitive result or at least a result that can allow your track to be compared to other tracks, especially true in the realms of dance music. Lets be honest a lot of sub genres in dance music aren't Sonically great: No dynamic range, extremely loud, clipping, brick wall limiting and over compressed! Some genres it almost seems that people are doing that on purpose.
If you are using someone to do mastering then yeh other things are applied, for example my mastering sessions usually have a mix (or all) of: Stereo imaging work, Compression, sometimes multiband compression, Mid/side EQ, Harmonic Exciters, Linear EQ, Automation and Limiting.
But a mastering session doesn't 'need' all of that.
Some mastering suites have fancy outboard gear but they do tend to charge extra for their use and (in my opinion) the noticeability is minimal. Someone couldnt really listen to a track and be like 'ahhhh yeh they used an external SSL and external EQ on that' .... or maybe some super audiophiles could but I doubt it. Digital plugins have come a long long way.
But if you really want to 'master' your own music you can very much get by with having a tight mixdown then applying some subtle compression and pushing a limiter for a higher average volume - practically just using your master as a volume boost. I mean essentially that's what the goal of a mastering limiter is.
mastering ISNT some super duper fix all magic so don't get too hung up on not knowing all that much about it. you are right about focusing on your mixes because that is 95% of your overall sound. Even the mastering wizards of the world cant fix a very badly mixed track so no sweat, you are on the right path.