How to become more polite?

Politeness is a thing that you need to bring it everywhere.
Whoever you meet you should use politeness. when you speaking, doing something, you should do it properly. But doing something politeness is not that easy, although sometimes it is flowing easily.
I oftenly think too much when i'm gonna text someone older than me, such my teacher, lecturer etc.
I think "is it polite enough when I text her/him like this?" I'm so confused. Then I'm looking for someone older than me and ask : "sis, is it polite to text my teacher like this?" It is happened when I'm about texting someone. But I think CALLING is better than texting. When you are calling someone what will you say just flow like a river. (>_<) and when you are texting someone you will think it oftenly.
Other case, if you still do not know about who the people are in front of you, then you should be polite to him/her. I know I'm not that old and not that young.
one day, I help a girl that i don't know her. She had a problem with her laptop. it's kinda it caught a virus. then I help her to delete the virus. She said "I had deleted it for many times, Dek (to address someone younger than you in Indonesia). But it is coming back."
"DEK." "oh my god... am I look that young so you can call me 'DEK'?"
Actually I'm happy when I'm look younger than my age, but it also insult me when someone younger than me call me like that. That's NOT POLITE when you CALL someone that you do not know using word that you think it's right. It's better to use word "MBAK" or "MAS" (to address someone older) than "DEK" to call someone that you don't know him/her.
Now, in action. It is YOUR right to smoke or not. But PAY attention around you when you are gonna smoke. There is someone that does not smoke also around you. When you smoke everywhere you like, then it is disturbing someone around you that never touch a single of cigarette.
So HAVE your OWN LINE to smoke as you like.

Oh My God, it seems that I'm angry here... >_< but actually I'm not. I just wanna write what are in my mind.
so finally, how to be polite? FOLLOW your HEART. Your heart has an instinct that can lead yo to choose a good one.