Great question! I myself wondered this many times prior to coming here (as it is my first trip to Indonesia). I asked a local acquaintance if I look like I’m from here and she said yes.
Purely just looking at me, people here will think I am from Indonesia (but they might still be wondering as to from which province in Indonesia I’m from, as people from different provinces can look and sound differently. Take as example NL. People from Friesland could sound differently than people from, let’s say, Brabant or Den Haag).
I think it’s mannerism that makes the difference; the way one talks, behaves, dresses, etc. As for clothing, the local acquaintance told me that the way I dress also makes it look like I’m from here (normally I wear non-branded loose-fitting clothing- even at home in Suriname). The telltale is… as soon as I open my mouth. As soon as I open my mouth and speak, people will -not just guess- but KNOW that I’m a foreigner.
I hope that I have answered your question(s). As to Instagram: yes, I will definitely share photo’s whenever possible!