one of the things i find helpful is to read through a lot of posts in whichever specific forum you're about to post in (if possible) to get a feel for the regular posters
usually then i can tell the users that may respond to my personality negatively so i either take into account that specific user and write my post so that it's less likely to illicit a response from them
or i just take into account that's them and if they reply to mine negatively then i know that's just cause that's that user and they're like that
not sure if any of that made sense but that's how i manage it (mostly i just lurk and don't post much)
i get so shaky when ppl respond rudely or negatively to my posts