Rule 1: No one wins a flame war

There was a time, in the heyday of the Fidonet echomail forum Life, the Universe and Everything, when forum posters could indulge in online conversational blood sport and then go about their daily activities, hold down jobs, raise families and generally show their faces in public.
Even if you "win", it will likely be a pyrrhic victory because your online identy dogs your corporeal self.
Be aware that some people ("trolls") bait others; don't rise to it. Consider everything posted about you, even if you weren't the author, to have a direct, immediate and lasting impact on your personal and professional lives.
Rule 2: You are judged by the company you keep
As ancient tribes gathered for succour and shelter, cliques formed and power plays ensued. You are rated by the people you choose to reveal to be part of your network so choose wisely and strategically.
Rule 3: Quality not quantity
Your network should enhance your understanding and enrich your life.
Some are like Fowles' Frederick Clegg to whom collecting is an obsession and end in itself but your network isn't a score card; it's not how many people to whom you connect that's a measure of your network's value, it's the value they bring to your network that's important.
An intimate gathering of cherished minds delivers greater value and influence than thousands of those whose opinions have no weight or import.
Regularly and ruthlessly prune those who don't continually add value or who in other areas of life bring themselves into disrepute with you.
Rule 4: Be generous
Acknowledge and credit those who enhance your network through their posts or other activities. Forward their thoughts to those who would benefit from them.
Rule 5: Just between us
Know when to keep something private and when to make it public.
Not everyone wants to know what brand of coffee you drink (unless, perhaps, that's your business and why people join your network). Closely allied to Rule 4, it may be useful to sometimes echo a post to your whole network but other times you may like to forward a particular snippit directly and privately to an individual or subset of your network.
And for security reasons you should keep private information - yours and that belonging to others - to yourself and not relay it on electronic networks without appropriate security controls. That includes but isn't limited to private phone numbers and online credentials, sensitive photos and multimedia.
That information can be used to hack an identity.
Rule 6: Maintain the mask
We all wear, in the Joseph Campbell sense, a variety of masks. Some of us are comfortable presenting just one face to the world but for most a different mask is appropriate depending on the situation. Know why you are socialising and choose the appropriate mask or online identity for the circumstance.
Maintain separate online identities.
Rule 7: It will be used against you
Notwithstanding rules five and six, assume everything you post can and will be used against you especially if it is sent in the clear (unencrypted) on public networks. If in doubt, make a phone call or meet in an underground car park under the veil of darkness.
Read on to understand how you can argue yet keep it civil ...