Always look like you know where you're going, even if you don't. Look like wherever you are, you have every right to be there. I can always spot people from more rural areas by the look in their eyes, they always look lost and a little overwhelmed. I'm not someone up to no good, but if I was I know who would make an easy target by that look. I see those sorts of people approached a lot. Looking confident is key. It's ok to be "rude" and not talk to people that approach you, 90% of the time they want money. You're likely going to see homeless encampments. While I advise not getting too close if you can, MOST of the time if you don't bother them they won't bother you.