Is your fuzz killing the buzz
One of the biggest communication errors I constantly encounter is the using of industry buzzwords, jargon and acronyms. This practice can and usually does, create annoyance, at best and misunderstandings at its worst. My advice is work hard to get the fuzz out of your communication style. Oh and often the lister will just see you as someone who is trying to show off.
Check for understanding
Can everyone define exactly what you mean from what you say. No some concepts can be hard to explain so you must periodically check the listener knows what you are on about. The are two ways to do that. You can ask do you have any questions which is OK however its better to seek a explanation from your listener. That can be difficult however the best way to do that is to ask the listener this question: "To ensure I have conveyed my meaning well do you mind putting what I am saying into your own words so we perfectly understand each other." Note: Never ask the question "do you understand".
Don't waffle, be succinct
Another common complaint I hear is that many people waffle on or go round in circles rather than getting to the point. Use short and well considered sentences and words to convey your message. Get to the point of your communication early, don't go into a long winded wind up. If the lister wants background they will usually ask for it, or you can ask if they need more information.