Stuff a sarong in with your sandals. Place over dodgy pillows, as a towel or to cover your head or legs when you enter temples. Just seeing tourists wear clothes that are inappropriate to the local culture can make local people feel marginalized.
Save displays of affection for private places…in some places kissing on the street is considered almost like having sex in public.
Grab a phrase book and try the lingo at the market. It will break the ice, show some effort and make people laugh.
Leave unsolicited photographs to the paparazzi. Show respect to the photogenic fisherman toiling to earn a daily wage less than the cost of your lens cap. Offer to show your subjects the image on your camera. You’ll attract a group of new friends the size of a footy team! Don’t offer to send a photo unless you really mean it. Just like at home, avoid making promises you can’t keep.