Travel, travel, travel! Been about 20 times, about 1 month each time to Sumatra, Java, Bali, Lombok, Sumba, Kalimantan, Sumbawa. Speak the language. Know the social and artistic culture and crafts/arts/textiles (since I`ve been importing from there for 14 years). I also know specific hotels, sights, even restaurants. But please don't ask me how you can move there/live there permanently/get a job there. My expertise is for travelers, not permanent residents.
My expertise in antiques, crafts and textiles is formidable:-).
Self-taught knowledge of conversational Indonesian. Professional dealer in art and handcrafts.