I noticed that many people seem to hate when others are rude and when they themselves are received as being rude so here are a few guidelines one should follow to veer away from being rude and meeting those who are rude.

How to avoid sounding rude:

1. Do not make any racial, cultural, or ethnic slurs when putting anything on the internet
2. Do not put anything that could be perceived (as per rule #1) on the internet
3. Do not be sarcastic, it does not work in your favor
4. Do not give your opinion to people
5. (Concerning rule #4) If you must give others your opinion tread lightly and use the correct amount of words to explain your viewpoint
6. If you think you may have been offensive include that you didn't mean to be perceived as such
7. Do not rant, chances are you will be ignored and you'll just be brushed off in the end

How to avoid rude people:

1. Always imagine what they might be going through first, take a moment to see things from their point of view before things get out of hand
2. Check for sarcasm, but don't try to reply with a "thank you" or by getting angry at them, chances are that it will only escalate
3. Leave trolls to themselves, fueling the trolls will only excite them (if you didn't know this already)
4. Always, ALWAYS, avoid large communities that don't have the same interests/ opinions as you, because chances are that you will say something that will upset someone
5. (Concerning rule #4) If you are polite in said circles you may be accepted but this is rarely the case
6. If someone is being offensive, just leave them be, don't try to retaliate by responding back to them, only report and move on
7. If all else fails stay off the internet

I hope these general guidelines help you to avoid those being rude and to in turn avoid being rude yourself. Thus making at the least this little corner of the internet a much more polite and habitual place.