Always use markets or places where people can speak in English.
This way you will not get cheated and will be able to understand what they speak. Never ever try to learn Tamil. Trust me you will loose more than gain if you try to learn this medieval language. If you try, first casualty will be your English, second will be the change in personality. I can safely vouch for it.
Now you will ask me how come I stayed here for such a long time.
Well, I worked almost isolatedly and was lucky to be under people who were from other parts of India or stayed in other parts of India. And I had a good run. Nevertheless, I had to spend many sleepless nights to get my job done. But I loved it, doing everything on my own. That I did as I am bachelor.
If you have a family or you are planning to have a family shortly, never ever think of working in Tamilnadu. In case you come, ensure to follow the rules and have your own friend circles. Otherwise, this village city will be a HELL.