Speaking the lingo has got to be #1.
If not, you're dealing with sensory deprivations akin to being deaf and dumb - you just don't know what is going on around you.
Some people seem to be born with an aptitude for learning languages.
I wasn't, but I overcame it to learn Thai because I didn't want my wife and our two daughters to see me as an illiterate who couldn't speak the language.
A close second would be a good marriage into a decent family.
Thais take care of their own, and that would include a farang who has lived among them for many years as a husband and father.
Family means everything here.
Your position in the family defines who you are.
Without one you are nobody.
Farang tao-nahn eng.
Most expats come here too late in life.
Too late to learn the language and attain some degree of literacy.
Too late to attract anything better than a mercenary woman and become a cash cow for her greedy relatives.
Living among low-life Thais in some cesspool like Sleaze-by-the-Sea, or leading an alienated hermit-like existence surely explains the Thai-bashing and general negativity so often seen on the forums and elsewhere.
Now that so many Faranglands have changed out of recognition and gone to the dogs, these expats are stuck here - they can't go home again.