I learned the hard way over the course of like 6 years mixing projects i put out.
It requires an ear for detail, and at least some understanding of frequencies.
I dont think of mixing as being easy to do 90% of the time, because you have to
essentially take a song apart, and find the elements that work and dont work.
make things blend together in such a way as to make listening to what you end
up with easy on peoples ear. peoples voices are different and require different
techniques, and different tracks affect the way people sound on them.
Believe me, i'm not all-star, but i know what i know, and when i do a mix for
someone they can clearly hear the difference.
As a producer you need to know a little engineering for the sake of knowin
what to tell an engineer if you're having someone else do it.