Humility and patience will clear the path. It's probably best not to touch people, especially on the head. Entire essays have been written on Thai sensitivity to this and the apparent insensitivity of it's producers. Money Exchanges are best done at banks - Exchange windows on busy noisy streets are easy places to be distracted, confused and occasionally taken advantage of. Theft and cheating is NOT as major a problem as most places, but they do occur.
Awareness is always a good idea.