I actively do not role play with people who create these over-exaggerated "broken" characters. Teenagers and young adults, especially (though obviously not all), romanticise mental health disorders. Is your character sad because someone died? Depression. Is your character easily distracted? ADD...
Very minor Persona series spoilers.
The Persona series is based on Jungian psychology concepts, so it's worth looking into those if you want to make your own version. For example, the masks in P5 or the glasses in P4 or the guns in P3 all have very symbolic meanings that relate back to those...
For me, it's people who up and disappear. I can talk to them about, literally, anything else I might have an issue with except that since they disappear on me.
For you, though, try messaging people privately to talk to them about things beforehand. I never do an RP without thoroughly talking to...
The more detail, the better. If text does it for you, then so be it, but I know a lot of people like to use visual cues with their writings and that's fine for me. I'll provide whatever a person wants when possible.
I'm sure things like grammar and spelling have been brought up a thousand times in here, so I won't touch on those. My absolute biggest two are (1) not being honest and open with me and (2) bailing without notice. For the first, it's hard to get a read on some people over text, so I make sure to...