When you are trying to express an idea to other people, there are a number of things that can go horribly wrong. Most of these are your responsibility. Not FAULT, but responsibility.
1. First, you have to ensure that you have an idea to convey. Word salad is not communication, neither is "look at meeeeeeeeeeeee!"
2. You must make sure that the definition of the word you are using is defined properly, especially when there are two or more definitions for the word or subject you are dealing with.
3. You must ensure that you are speaking to your intended recipients in a manner that will allow them to listen. If you speak down to someone, for example, they won't listen. Saying that "they should be able to listen anyway, and not take things personally" is bullshit. It is YOUR responsibility to make your message clear and receivable, NOT their responsibility to look past your bullshit at the timeless wisdom embedded underneath.
4. Do not assume the recipients are ignorant concerning basic things.
5. If your recipients aren't getting what you're saying, or are hearing you but applying the wrong definitions, etc, then the signal was bad. Restate your case or correct the definition problem. If they insist on using the first definition to avoid being wrong (see below), shit on them from a great height.
If you are listening to someone else, then you too have certain responsibilities.
1. LISTEN to understand, NOT to reply. Ensure that what you are getting is what they actually SAID, not what you WISH they had said or EXPECT them to say. This is the NUMBER ONE CAUSE of miscommunication and endless piles of butthurt.
2. Not everything is personal, and not everything is about you.
3. When responding to an argument, respond to the idea being conveyed. Picking away at sentence structure for any reason other than establishing clarity isn't communicating, it's being a dick.
4. When you feel the urge to post something witty or pedantic in response to serious posts, punch yourself in the genitals at least twice first...UNLESS YOUR GOAL IS TO ALIENATE THE OTHER PERSON ENTIRELY. There is nothing as infuriating as typing out a meaningful post and then having someone make a painfully obvious/stale joke, or correct you on some minor point that has little to do with what you are trying to say.
5. Derailing the conversation to show how intelligent or informed you are is not productive (ie, it doesn't make you look intelligent or informed, it makes you look like the poster child for Dunning/Kruger. For example, if people are discussing something that occurred in classical times or biblical myth, spare them the History Channel interpretation that you assume nobody else has heard. Everyone has. Shut up.
For both recipient and sender:
1. If it turns out that you are mistaken, do not try to move the goalposts or change the definition of words to avoid being wrong. You're already wrong, and you can either acknowledge that (honest, your penis will NOT fall off for admitting error) or you can look like a complete fucking moron by trying to argue your way around the inconvenient truth.
2. If the person you are talking to is more interested in scoring points than talking, walk away. If they are more interested in showing how smart they are, walk away. If they are an idiot like Holist, point and laugh. Then walk away.
3. Winning an argument on the internet will not attract mates. Likewise, losing an argument on the internet will not RUIN YOUR LIFE FOREVER.