What is the key factor to make excellent communication with others?

The main key is Listening.

As you know , Communication is a two way street. After you've said what you have to say, stop, listen, and look for feedback and clues of comprehension. While the person is responding avoid any impulses to cut them off or listen only for the end of the sentence so that you can blurt out more ideas or thoughts that come to your mind. Respectfully give them your full attention. When they are finished, to ensure that your message has been clearly and correctly understood

good & active listening

Listening

Maybe the key is to understand our audience.

For example, if we want to convey a message then it is important that the receiver can understand us. We have to choose our methods accordingly. If communication is too complex (Numbers/Graphs/too much Text) for the audience than listeners will either get confused/irritated or bored.

If we communicate to gather information then we need to listen carefully and ask follow up questions so that we understand the exact picture.

If we listen to an upset customer then showing empathy is vital.

Sure there is more...

understanding of each one and how he thinking and his weight to be able to make the good comunication in the best time with the best issue

 We may understand people, BUT, they do not really know we do.

The key factor to make excellent communication with others is to interact with them in order to make them sure we understand them.

Communication skills are vital for any kind of persons.a good communication helps to makes a good friend.listening is the important factor of a good communication.listening the good things and answer the correct things

Positive thinking and then converting thoughts into appropriate words and gestures. 

Knowing who your audiences are is the key to a successful communication.  You have to know what kind of crowd you are talking to or trying to put your point across.  if you are talking to children, would you want to use big words? I didn't so.  You want to use words that are easily understood by the type of audience you are addressing.  The Second thing is, you have to be able to make your audience relate to what you are talking about by using your experience or experiences that have already happened to them. 

I would have to say it is empathy, without any doubt. When you are able to foccus your attention on the needs of the person before you, you will communicate efficiently and successfully.

listen and understand then  reply properly which makes a complete communication