make friend and teach vietnamese for foreigners for free

That's a good idea if you are free 
Welcome!

Welcome...

Free is good... (( the other Expats ))
that are charging.... (( WILL NOT BE HAPPY ))

LOL

Yeah! I encourage someone to held a weekly meeting which can help Vietnamese to improve English and foreigners can improve Vietnamese. That means during meeting each side can only speak (with help) the other side's language.
The meeting must has a topic notified 1 week in advanced so that participants can prepare before joining.
That's the way I learn languages.

That is a wonderful idea a win /win for both.I try every night to speak English to at least 2 people.I know the viet people are happy to pick up a couple new words and i get the same thing in return.I don't do the bar scene,though i am one of those retired men living on the beach of Nha Trang.I would like to find a place like that in Nha Trang. Last night I was invited to sing and chat with 20 or so locals.The children all had a chance to ask a question.What an awesome night!!!!!

Do you really mean that?

Yes !!!Why would i write if it were not true.I am not here to impress people only trying to get a better understanding of the people and country that allows me to be their guest.