1. Under no circumstance should a fellow human being be allowed to be in a state where it becomes impossible for them to seek employment and housing, should they so choose to. Opportunities must exist for bootstrapping oneself.
2. Dedicated facilities for treatment and help should exist in open areas rather than in urban centers. Ghettos and concentrated areas of poverty and drug use are not hospitable places for recuperation.
3. The person in need must have guarantee of good quality food, water, and shelter, if they so wish it. Dumpster diving is not an acceptable behavior either for the dignity of the individual or for the functioning of society.
Let me expand on why these were chosen. There are many reasons why homelessness is prevalent in large cities rather than in rural areas. But if I was to state one major factor, it's because cities provide a better means of survival due to services such as shelters, kitchens and communities that are sympathetic to their plights. If these services existed in rural areas in open facilities dedicated to healing and reinvigorating those who want to leave this kind of existence, then that would be preferable to keeping a large swath of people in squalid urban jungles. However on the flip side, the implementation of these facilities have the danger of operating like work/interment camps, ghettos, or reservations, and therefore they likely should be kept small and set up by those who are knowledgeable in homeless life, preferably by those who have experienced these conditions. The facilities should provide lodging, food, mental and medical help and perhaps even a clean supply of drugs for those who are heavily addicted and suffering tremendously (consult a substance abuse medical professional on whether this would actually help. It likely wouldn't but might be useful in some therapies). For those who wish to re-enter and start climbing the social ladder, they should be allowed to take up jobs within the communities. A properly run community would ideally be self-sufficient enough to need minimal governmental assistance. And for that to work, they would likely need their own economies and means of production and interface with the larger governmental organizations as trade partners. This would be one possible start on providing a social floor, a return to the land and nature for healing and rejuvenation.
Once the platform is in place, the second step is to bolster the social net so that most people don't hit the floor in the first place. This has traditionally been taken care of by unemployment benefits and other social structures aimed at providing jobs. The setup makes sense in a traditional capitalistic society, where a person needs gainful employment to earn a livable wage and use it to sustain a family. In the absence of a suitable wage, the person needs charity to survive, almost as a warning or an ominous precursor to the next step awaiting them at the bottom of that social ladder. To keep the system functioning, it's important to have high employment as the funds needed to pay a large number of unemployed people can quickly drain the government coffers and result in economic failure. It's certainly a fragile system, and likely there's plenty of room for improving the robustness and reliability of it. In a world of so much need for goods and services, it makes little sense to have such a thing as high unemployment, if money was fluid and circulated to all parts rather than concentrated to specific areas only.
The third step I propose is to ensure that the ladder is fair and climbable, rather than a ceremonial thing, frequently circumvented by those who use escalators or jet packs. An economic system where meritocracy is only lip service and a facade is certainly a system of bold-faced lies and must eventually fail as an incompatible inefficiency to the dream of a harmonious humanity. Therefore favoritism and positive reinforcements of mediocrity in all facets of the social ladder and society at large must be challenged and called out.
Although the proposal requires a tremendous amount of strength and resolve to bring it about, it is necessary and will become crucial for us to have a functioning society going forward. Our outlook must also transition to measuring the wealth and maturity of a nation by examining the conditions of its poorest and the most vulnerable, rather than figures and averages of various skewed and unrepresentative financial metrics. Human dignity must be upheld above the numbers, not the other way around.
Judge the tree by its fruits. But remember to...
Wash the beam out of your eye with soap.