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Getting off the street can be difficult and is not something to think lightly about. I've been homeless about 7 different times since age 11 or so. It doesn't really get any easier each time, neither, and thankfully I haven't had to sleep outside or in my car, but I did sleep under my desk at my first job for about 2 months, and got some weird looks for it. Really, anything is doable if you can get a shower and clean your clothes.
Not having a permanent address is a pain in the ass, but you can feasibly use the address of an abandoned house or something, though I haven't tried doing that before, and it meant for me having to use a family member's address. At least in the US, you'll need to get your social security card and a state ID, and most likely your birth certificate with multiple proofs of residency to get your ID. YMMV. So long as your criminal record isn't fucked, getting an apartment requires about 3 months rent up front besides needing a security deposit for incidentals or pets. Check out >>>387 for advice on doing that part and DO NOT SKIP ANY STEPS. If you can rent a room or get into a shelter, if you gotta get sober, if you need a phone, if you need a car, it's ALWAYS best to do as many of those things up front instead of raw-dogging homelessness. You might end up having to live in with the worst roommate ever or in a motel, at least you can hopefully change your situation to find a better roomie, a cheaper spot, something, as long as you can minimize your exposure, because exposure can and will wreck you quicker than anything else you can prepare for. Don't do stupid shit that can put your ass in jail while you're on the street because it means you will be starting out from scratch. I've heard that as long as you have an ID you can get into a halfway house, and it doesn't even have to be legit, that it can literally say you're Elmo, taped together, or whatever, though I don't know anything about how well that works. There is likely a waiting list depending on your area additionally.
Spend as much of your time while homeless looking for a way out, because it definitely is a choice (and not a good one) to stay out on the street, and it's only getting harder by the year.