I can agree no more with the above answers... great! to wrap everything up, it's the tone of your voice, facial expression and gesture that would lead you in voicing out a "gentle" talk. I personally believe that whatever cultures or beliefs we have, still, we can have a good talk if we both speak with mild tone and wearing a smile on our face... God bless to you as well... :)

That's a tough one. Abuzel is completely right. You should know the basic polite phrases, but it also does depend a lot on the environment you're in. i mean you would behave differently and with a different degree of politeness around your peers or let's say around people you're doing business with. In any case it's right to avoid harsh behaviour and show yourself kind and openminded. The problem is that the standards for harsh or polite behaviour differ not only between different social levels (peers vs. business partners) but even more between different cultures. Things that might be considered polite and friendly in China might be considered differently in for example the US. It's even the same between seemingly close cultures. I've got quite some experience in german-american intercultural interactions and i'm still running into intercultural misunderstandings from time to time. you should ask someone of the culture you want to interact with to coach you especially on "friendly" group behaviour. This person basically needs to interact with you and then be willing to afterwards tell you what in specifique you could improve about your behaviour or language. It's really hard to just tell you some phrases to solve your problems.

well, first of all use words "please" "thank you" etc Also - speak calmly (if you speak live with someone) do not make harsh sounds. Avoid using shorting words "Thank you"-"thanks" "Hello"-"Hi" and so on...