As a Mexican living in Malaysia who every day gets confused as local but never as tourist and blends in doesn't matter if is New Zealand, Spain, Germany, Brazil or Indonesia (in all those countries people have assumed i'm local) i would say no selfie sticks, gopros, no big camera hanging from your neck, no lonely planet/map while walking on the street and PLEASE if you visit Southeast Asia no singlets shirts printed with name of beer brands or padi conical hats!! Those scream tourists!! Same in Mexico if you walk with a big sombrero hat! Dress as local, i have realized here in Kuala Lumpur it's so easy to identify who is a foreigner living here and who is a tourist just by looking at the clothes. We expats even tend to even wear jeans, when a tourist probably would never do while in KL!!
Also, do your research of the place you are visiting before getting there, the colors of subway lines, main stops, landmarks, how to get from A to B, the main food dishes, don't ask for food substitutions/changes unless religious/allergy concerns (don't ask for a curry soup less spicy if the stall is just a lady with a big pot of soup serving the bowls in front of you), if you need directions just check your phone (those days is so easy to get tourist simcards with data plans), learn a couple of words in local language. Actually, it's easy to blend in, to put it simple look at the obvious people who look like tourist and try not to act/look like them.