Learn and study Indonesian language, or also known as Bahasa Indonesia, is one of the option for an expat who live in Indonesia. It is a good thing to know that many Indonesian people, who live in big cities such as Jakarta, speak English well.
However, there are many benefits for one who learns bahasa Indonesia. The abilitity to communicate with locals indonesian are mostly helpful. It will help you go through daily lives, also will help you go through office lives, avoid many problems. Especially if you are a traveler in Indonesia. Bahasa Indonesia is used as formal language in the whole country. People may use local ethnics language and dialect, but all of them understand bahasa Indonesia. So you can travel anywhere with ease.
What is the best way to learn it? You decide. If you are a self learner person, just browse the internet. But if you are a person who need to be guided, learn from a guru bahasa indonesia for expatriate is an option. The teacher can be an Indonesian you meet around you, a hire a professional bahasa indonesia tutor. Or if you want to achieve a certain goal, going to a university to get Indonesian course is also possible.