I feel the need to add this because I saw a couple of posts where the homeless were basically dehumanized.
The first and foremost thing to realize is that you need to treat the individual as a human that is simply experiencing some very real human problems that they may bear no responsibility for at all. They are not bad people, they are not people who choose not to work, or take on responsibility. They are people just as everyone is. Part of the problem with the lack of services for the homeless is that people generally assume that they are lazy, or alcoholics that like the way they live, etc. etc.
This is a case in point where "There but for the grace of God, go I." needs to be the first thought in your head.