[CGW]

Size matters. Small 35mm cameras with a 28mm to 50mm are unobtrusive(e.g., Nikon FE/FM series or FG bodies work best for me). Larger AF film and digital bodies with honking big zooms+hoods are asking for trouble and/or unwelcome attention. Chimping also draws notice once it's clear you're not playing with a phone. No one seems to notice when I shoot my Bronica SQ-B with a WLF or even a hulking RB67 on a tripod. I assume people think anything that takes that much time to set-up and shoot couldn't be harmful. It's the "hunter-drawing-a bead" stance that's considered provocative and intrusive.

Behavior matters, too. Stalking, chasing or cornering people is dumb. Asking permission seems defeatist. Watch some footage of Cartier-Bresson at work. Simply blending in and patiently waiting for shots works, too. I've used a Manfrotto SuperClamp and a small ballhead attached to Toronto's curbside bike racks for great shots. With pre-focusing and some DOF, I used a cable release to catch people walking by or stopping to check-out a shop window just by tripping the shutter a few fet away from the camera.

Overall, it's totally dependent on the street gestalt of the area, something you have to figure out by yourself.