The most important thing if you want to be understood is to understand your self first. Until then whatever you say could be open to misinterpretation.
If you are being misunderstood then try and write down what you want someone to understand.
Get it clear in your mind the point you are trying to make first.
You might think you understand yourself but if you are being misunderstood then perhaps you need to clarify it in your mind first.
If you write your ideas down you can read it back to make sure the words you choose are as clear as possible.
Then try to communicate again.