TED talks are an excellent place to find short, clear speeches on many interesting subjects. This 10-minute speech covers bad habits to avoid, good habits to use, a toolbox of communication skills, and public-speaking warmup. The speaker is speaking UK English, and the vocabulary is at an academic level.
This site addresses a common problem that people have when communicating in a new language. How do you understand what someone is saying to you, and keep a conversation going. They talk about the importance of body language, as well as some useful words and phrases to get speakers to help you to understand them better.
One skill that is very useful is to rephrase what you DID understand, and repeat that back to the speaker. This is called Active Listening. It’s helpful to the speaker to know what you did understand, and they can easily correct you if you do misunderstand what they said. Nobody really wants to just keep repeating what they have said again and again, and a conversation will be very frustrating for the speaker and the listener if you just ask the speaker to repeat themselves. Try some of the tactics in the video, next time you meet someone new!
Here’s a great blog by a native Polish speaker who is trying to learn English online. Since most of the writing is higher quality than what the average native English speaker writes online, I think this method must be helpful!