Behaving properly when representing oneself, or ones company, is essential in order to maintain brand equity, trust, a perception of thought leadership, and all factors of reputation.
It's not that common
Treating people with respect and courtesy, just like one should treat their elders and people of standing, should be a standard operating procedure.
Emoticons help convey emotion
Believe it or not, it's actually a good practice to use smilies and other emoticons to help quickly and easily convey the mood or emotion at hand.
Keep personal information private
The world, including cyberspace, is not filled exclusively with trustworthy, loving people. Be smart, be safe, and protect your personal information online.