Language is a very important in our everyday lives. Although we may not all speak the same language I think there are some things that "should" be programmed into our brain. Now, I say this not as a know it all but as someone who could use a few tips and tricks every now and again.
Some people, although the other person may not say it directly, can tell how you are feeling just by your body language. Your posture, your hand and arm placement, and even sometimes where your eyes are directed. (I'm sure there are more but those are a few I can pick up on!) All those things give away some sort of feeling; anger, sadness, tired, happy, etc. Although we may not mean it that way it does come off like that. I have a habit of crossing my arms and my mother likes to tell me it makes me look mad but i do it because i feel comfortable!
Word choice and tone. I think it speaks for itself. In Hawaii, we have a terrible habit of constantly using "da kine." Its the slang for when we can't remember what "it" was. Can you imagine having a conversation with someone that couldn't remember what "it" was? Well if you can't, Hawaii might not be the place for you.
There are just some things that should be universal with language.