Hello Forum!

I know some of you might be annoyed with this question but here I go! Lol Anyways my question is basically this: I have been told in different forums that If I want maximum quality from a sound without distorting it I have to keep it the mix below 0.0 db like -0.1 db or something if I understood correctly. However from my knowledge the only way to keep a mix from a certain peak is to put a limiter on. However if let's say I have a mix peaking at 3db and then I gradually use a limiter so the peak never goes above -0.1db the sound gets squashed and creates a very unpleasant sensation for the listener.
So I guess my question is how do you make your mixes so loud without distorting and squashing them? Or maybe I should just go above 0db?
Thanks in advance very cool forum btw