I read a bunch of good books on communication and what stood out was that effective communication is mostly about strategies to get the other person to open up, while also sharing your perspective. It's about realizing that the other person may get defensive and insulted about things where you meant no insult. Accept that as the normal state of affairs, even with reasonable people, and then move on to dealing with that. Accept that most people, much/most of the time are poor communicators/listeners, and set up your framework appropriately. There's little point in becoming very good at communicating your perspective if you don't account for the fact that misconstruing what you say is virtually the norm. Don't account for it by repeating something verbatim (the worst) or by finding N different ways to say the same thing. Solving it is by getting the other person to open up about what they are hearing.
Everyone says "listening is more important", but that's a bit inaccurate. You can't listen if the other person doesn't talk to you (as Martin experienced). Effective listening is actually about getting the other person to open up and communicate with you - I prefer to call it Active Listening.
Certainly, how you say things matter, but it's perhaps 20-30% of effective communication.
One book put it clearly:
Stage 1: You worry too much about how people will respond to what you are saying, and you take ownership of their negative responses.
Stage 2: You stop worrying about it. You realize that as long as your intent was fine, and your communication was not misleading/unclear, you are not responsible for the other person's feelings. You free yourself of that baggage, and speak without worry.
Stage 3: Even though you are not responsible for other people's feelings/responses, you have empathy for them and decide to help them out and find ways to find ways to have them open up to you (without feeling manipulated, etc). At this stage, you don't care when someone insults you or shouts at you for something innocent you said, but you don't drop the conversation either.
Many people get to Stage 2 and stick to it. It's a better place to be than Stage 1, but you have a higher chance of people perceiving you as uncaring, rude, etc. Those who want to get better at communicating try to get to Stage 3.