I learn Thai starting about 23 years ago with a teacher in Bangkok, learning the Thai characters (no transliteration) and learning to read first, then correct tones for the different letter groups, then speaking in real-world situations. I learnt Lao language with a teacher in Luang Prabang, mostly to understand where a word common to Thai and Lao have different tones. I learnt to read/write Lao myself, using my existing Thai language knowledge. Now I'm self-learning Burmese, reading and with correct pronunciation assistance from native Burmese speakers. I find myself in situations in Myanmar where no-one speaks English (or are too shy to speak it!), and then I'm forced to speak Burmese. Amazingly (to me), they seem to understand me...