I have to use headphones and I have heard that it's not ideal. I use ATH-M50X.
Can Someone explain what "mistakes" or tendencies that mixing on headphones cause?
Thanks
The biggest mistakes tend to come from perception of stereo field.
With speakers your left ear hears right and left, as does your right ear.
I.E. Cover one ear and you still hear everything.
With headphones if you only have one ear on, you only hear one side of the mix.
This means that our perception of width is accentuated and our perception of volume of central information is skewed, on cans.
Generally that translates to listening on speakers and wondering why the mix doesn't sound as wide, and why the vocals/bass/snare are too quiet.
You can also run into difficulties picking up cancellation, for the same reasons.
The lack of bleed from L to R means that if you have hard pan left and right tracks which cancel each other to some degree, that will be much more obvious on speakers than on headphones.
In short always, at least, check width, central information volume, and cancellation, on monitors once in a while, if the lion's share of work is being done on headphones.