I've been here before and while I don't wanna take the time to write an entire guide, the short of it is you need to fucking hustle and start now.
As of now you are a goddamn sales agent. Your product is yourself. Always Be Closing and No Means Next are your new mantras. Don't be afraid to stretch the truth if it means you live another day. Your life is about to be very different and difficult. You are now a pariah. People will not see you as a human being. Get used to that fast and this'll be easier.
You need to find a place to sleep and get food, that's paramount. You need to find a way to keep groomed and clean, people are fucking assholes to dirty humans. You need to find a way to clean your clothes, too, because people view you as subhuman if you can't wash your clothes once a week.
Go to a church. Make up a slightly more tragic back story. Get good at this. People are gonna wanna hear your tale and its gotta mostly conform with their preconceived notions about you but should defy them only in one part or another. They're gonna be demeaning as shit to you while pretending to be nice, be ready for that and play into it. They love that shit. Be ready to switch churches once the congregation gets bored of helping you, which they will. Christian denominations will probably give you the most in the onset, but also they actually give the fewest shits. Mosques and Hindu temples will give you the best foods, but YMMV on how much assistance they'll provide.
If you can meet and talk with a Rabbi, this is the best option. No one helped me more directly and honestly than the Rabbim I met on this journey. Everyone else gave what they thought was the Platonic ideal of aid. The Rabbi would listen and try to help like a real friend.
Keep clean. It's so important for getting a job and recognized as human in society, it's so wildly important.
You wanna find suits and "nicer" clothes at thrift stores. Don't worry if they fit poorly, a shitty suit and tie makes you more human in the eyes of society than a ratty t shirt.
Apply to min wage jobs like mad. You can use the church as an address. That'll mostly fly, but also when you tell the pastor you almost had a job but they needed a physical address, they'll more than likely tell you to use theirs. Look for places that'll pay in cash, i.e. aren't big brand businesses. Retail is mostly big corporations now, don't discount them entirely, but focus on small business shops like pizzerias or delis. Someplace that isn't gonna have some binder of SOPs or corporate oversight. Food places are great because they usually have left over shit you can ask to take home. Anything going into the trash, that can be yours.
Once you get a lil bit of money, hoard it. Don't let anyone know you got cash. You want a car or some other way to travel longer distances so in case things go tits up, you can bail. A $10 a month gym membership gives you a shower and place to shave. Burner phones let you keep in touch and network when you can't use the computers at the library. Dunno if it still works, but I got a lil cash going doing retail arbitrage via Craigslist and Facebook. Do all your exchanges at a police station. Unless you "look homeless", then the pigs will harass you. Do it at a Walmart lot with lots of cameras during the day. Don't get into the drug trade unless you know what you're doing, you'll get hurt and bad.
Speaking of substances, don't turn to drugs. They're too expensive to really help anything. Booze, though, can be useful in small amounts. It's extremely calorie dense, and a buzz is nice, but 1) you're gonna need your wits at all fucking times, 2) no one respects an unhoused drunk
Shoplifting is easy. But don't do it as your main way to acquire things, do it while buying other stuff to stretch your dollar. Your legitimate purchase is your ticket into the store. Be smart. Look for cameras and employee eyes. Take small things to practice.
High calorie food sources are great when you can't get much food. So is stuff you can keep in your mouth a long time, helps keep hunger away. Chew jerky was a personal favorite. Bags of nuts are good, too, but be wicked mindful of salt intake and make sure to drink lots of water. Many libraries and parks will have water fountains of some kind.
Convenience store hot dogs are great. They're cheap and you can abuse the toppings for extra food. Do this when they're busy so they don't see you loading the box with relish and tomatoes. You can also buy chips and pour the pump chili and cheese over em if no one is watching you.
Come up with stories to tell pigs as to why you're sleeping outside (got kicked outta home if you're young, spouce kicked me out if you're older, etc). If you get caught, don't sleep there again for a few weeks. Especially if you're sleeping in your car, the pigs will take it from you, they are monsters, never ever trust them.