1. Unabashed criticism.
"You know what your problem is?..........."
Refer to this: http://chovblog.blogspot.ca/2013/04/shoulds-and-prejudices.html
2. Negative comparisons to others.
Whether or not your opinion is asked for, it is usually not a good idea to say:
"That's not normal behaviour" (Define normal?)
"My mother did it differently." (Just DON'T. Seriously. If you don't understand why....gah...)
"Most people........" (Likewise)
"More educated people............."
"In my old job....."
"Where we used to live............."
You get the idea. If you cause offence, people switch off. Comparisons are frequently offensive. The object is to get them to listen. So don't turn them off before you made your point.
See above. It's not even relevant.
4. Old news.
Although you may be repeating yourself, or the problem being addressed has been repeating, deal with the situation in hand. And therefore do NOT say "I've told you before.................." unless the repeat offence is genuinely the crux of the problem. Usually, it isn't.
.....is not helpful. So don't begin if either party is already angry, and if either of you gets angry during the conversation, pull back. Words spoken in anger cannot be unsaid, and they may not be the truth. Other emotions can be equally distracting. I'm going to go into this in more detail later in the week.
On a related note, shouting tends to turn people off too.
This isn't a lecture, it's a discussion. Talk AND listen.
.....have a purpose in our world, but they should be a last resort when diplomacy has failed hopelessly. Even then they should be phrased in such a way as to not be personal.
"....or else" is not advice. It's a threat.
Any complaint should include a solution, should be presented to the person with the power to take action, and should present a case that what is happening (that you object to) is bad for all concerned, not just the person complaining. This encourages action.
9. Gossip, rumours, and lies.
Are not appropriate ways to communicate, ever. Withholding the (whole) truth is an appropriate strategy in some situations, but care has to be taken even there. There is such a thing as a "sin" of omission.
10. Folding your arms, looking away, huffing, eye rolling, tutting, etc.
Dismissing a point of view ends communication. Right there.
You don't have to agree with what you are hearing, but hear all of it.