I used to have that problem when I was an overly active member and engaged in conversations and discussions with people all the time. But now I am rarely around the boards and when I am I never really have that much to say anymore.
The only thing I've really learnt to do here is re-word my arguments/opinions so that I don't come across so hostile. Also, If I'm in a bad mood, I know not to even bother replying to something - I just end up saying a load of crap that I don't mean. Also, sometimes people bring up topics about things that have obvious answers. I don't see the point in discussing them other than to give people a chance to sound pompous. Screw that - I just ignore the thread. Some topics go round in circles so many times that I just think, why bother even posting? Other than that...nothing's really stopped me from saying what I mean. I've caused controversy before, but I'm not scared of it. After all, I'm still here, aren't I?