I told you these tipps were going to be very basic and this one is particularly obvious, but perhaps not for everybody:
Not every thing you do wrong at the mixing stage will actually hurt your mix badly. Professionals will surely recognize deficiencies and many a decision might be a matter of taste (good or bad). However, if you screw up the low end (<150 Hz) or the high end (>15000 Hz) of the mix, it will affect even the average listener’s impression, because:
- too little low end sounds weak
- too much low end sounds obtrusive
- too little high end sounds muffled (and might crush your reverb)
- too much high end sounds sharp and can be tiring to listen to
My approach: I first use headphones with over-emphasized bass in order to get the low end right. Then I use light headphones that have little bass but a lot of high frequencies in order to smoothen the highs. This way I get the mix to sound okay on most devices without losing too much detail.