Ditto on what you said. Grew up in similar circumstance but the bad sectors had to be transited. You also learn to pay attention to eye head swiveling towards an area you can’t see directly, say beind a parked van. One person turning his attention, may be nothing, two or more, especially not moving together, might be something. They start moving a bit more quickly you might want get some distance before moving into that zone. Watching two or more guys approaching begin to split, left and right, maybe center guy slows up, you’re watching a box open up, guess who’s the present.
You need to also catch “micro-expressions”. There’s some great stories on the net about this & how it’s saved people’s lives.