I try to adhere to the principals of:
reread the posting to make sure it is not just the author's limited grasp of the subject or language,
not replying when I'm annoyed but waiting till I've calmed down,
asking myself if what I said would unjustifiably upset me if someone said it about me, and
proof reading at least twice.
There are people and threads better off ignored. The hard part can be identifying which ones they are.
Flashing emoticons do little for me except encourage migranes.
And as for l33t sp34k ...