It can be so easy to think you are understanding exactly what someone else is trying to communicate, when in reality you are nowhere close to understanding. If you truly want to do your best to understand someone:
1) Let go of thoughts and pay attention to the other person.
2) Look at them while they are talking and try to read visual clues. Looking at them will also show that you are interested in what they are saying and usually helps the other person be more at ease.
3) Ignore your assumptions and biases. It is much better not to make any at all, but many, maybe most have these deeply ingrained.
4) Let the other person finish vocalizing their thoughts without interruption. Wait for a 3 second lull before responding. Deter any unnecessary rambling politely.
5) Check that each interpretation is correct by repeating your perception of what the other person said.
6) Each time after you have responded ensure that they have time to formulate what they want to say without interruption.
7) Ask questions pertaining to subject matter for further knowledge, better understanding and deeper insight.
8) Engage in a brief summary for a few minutes to cement knowledge and memory.