As much of a frequent reader as I may be, the one type of literary work I don't necessarily overwhelm myself too much with is photography books; specifically ones that go in depth on how to improve your portraiture.
There's many great ones out there but as far as developing yourself in this genre, what's worked for me has been the combination of looking over other people's work along with understanding more about how to approach people.
Eric Kim has written several times on what sociology has taught him about street photography and as unrelated as that subject may seem to the craft of taking pictures, there's a to to be applied, mainly the act of connecting with someone whom you probably want to approach and put at ease in view of the camera that's being pointed at them.
I'm very non-confrontational about asking permission to take a portrait of someone but I will admit to very often going out of my way to obtain one.
I had spotted Steven on his skateboard and Lindsay on her longboard riding along a not so congested Bushwick street and the speed at which they were traveling, the only way I would have been able to catch up to them was in my car. I jumped in quickly, passed them, pulled over quickly by a fire hydrant and managed to catch Steven's attention and introduced myself. The rest is history.