Since running away from my parents' home and having to arrange living for my first time out of my own means, I've learned a lot and want to share some advice for other young adults. (This article is mostly aimed at Twitter friends; I know a lot for whom doing this could be a reasonable decision in the near future.)
Documents and essential assets
You're immeasurably disadvantaged without government photo ID such as as a driver's license, non-driver state ID or passport. Without one of these, you pretty much can't get a job or housing. Passport is the best; as far as I know it works for anything and applies country-wide. If possible, also have a social security card, birth certificate, and any other legal documents you can get access to.
As much as I hate to say this, and believe me I hate to because phones are an abomination and should die in a fire, it's a borderline requirement to own a phone. Any time you apply for a job or housing, they expect a phone number, and a lot of web forms require you to input one.
A bank account and debit or credit card are extremely valuable assets compared to toting cash around everywhere. A lot of card processing machines will ask you for a PIN; if you don't have one, just try to enter an empty one and that usually works.
Obviously, you'll be renting. And you'll probably have to tolerate housemates.
A big bummer is that unless you have significant income and a good credit score, which you almost certainly don't if your position is anything like mine, you can't rent an apartment traditionally. They have application processes covered in some sticky red substance and usually require you to prove your income is 3x the rent. So searching on websites like zillow and hotpads is a waste of time. Your only options are alternative renting platforms like airbnb.
Some people say airbnb gives worse prices than traditional rent. I think that's bullshit: airbnbs nearly always include all utilities (running water, temperature control, electricity, WiFi) while traditional apartments usually include at most 2 of them; the rest are further expenses. I don't think airbnbs are actually a worse deal when you factor all that in.
Although airbnb is the most well-known alternative renting platform, there are several others.
Hotels are only an option for very short stays because they're about $100/night. That said, if you get caught unprepared and you can afford it, look for one because they're the only option where you can just walk in and get a room without any application process.
Rent (even if it doesn't include utilities) will take the vast majority of your budget. Food will probably be less than 1/4th as much as your rent. Assuming you accept housemates, expect to end up paying about $1000/month for your housing. Much more than that if you insist on not having housemates.
Also, get used to not getting a response. This is worse in the traditional rent system, but even on alternative platforms a lot of places will never respond to your initial inquiry. If you need to ask questions before reserving (and you probably do because a lot of listings leave major ambiguities about what's being offered), reach out to several options.
Finally, don't wait. This probably seems like obvious advice but I got screwed over a couple times by thinking I could put off the commitment for a few days to make sure I didn't find a better option. I couldn't. You can't; reserve as soon as you have a good option.
Tip about airbnb in particular: a lot of places give massive discounts if you book a month or longer, sometimes more than 50%. Another tip about airbnb: just because the airbnb form says your dates are available does not mean they are. Sometimes the form is wrong.
You want your residence to be within walking distance of multiple grocery stores (incase one doesn't sell something you need). When buying food, always look for alternatives until you find the lowest price. Check the nutrition facts and determine the ratio of dollar to substance. You should be able to feed one person on less than $10/day (I can feed myself on $7 and that's with some unusual restrictions making it harder).
When reading nutrition facts, always check the serving size and the number of servings included. Preferably do some research on nutrition too.
In my experience, delis often have a good selection of food items but much worse prices than larger grocery stores. Don't pay $5 for 8 cups of juice; a supermarket probably sells it for half that. Some delis also don't allow card payment, only cash.
And don't even think about restaurants, the prices are absolutely celestial compared to grocery stores.
There are basically 3 desirable traits of foods that usually come at the expense of each other:
Ease of preparation
There is one food in particular that I point out for having an exceptional combination of these traits: rice. You can literally spend $5 on enough rice to eat it every day for a month. It's also fairly high in protein and calories, and is easy to prepare as long as you have a stove, pot and lid. My procedure is: use 3/2 as much water as rice, wait for the water to boil, then put the rice in (lower heat to minimum so it doesn't boil over) and cover until the water is all gone. It only takes a few minutes.
Rice pairs very well with beans, which are also nutritious, cheap, and easy to cook. I put canned beans in a pan, fill with water until the beans are mostly submerged, cover and heat for a few minutes. Many sources say dried beans are much more efficient than canned ones but harder to prepare, but I haven't tried dried ones yet.
Nut butters are another extremely efficient food, on the order of 1000 calories per dollar.
I don't have much to say about this one since I've still never successfully been hired by anyone other than relatives, so I mostly lack the qualification to advise. If you have a skill set that allows remote work, like me (programing), you're lucky as that means you aren't limited to searching within a tiny area.
Determine your stability threshold. If you work 40 hours a week, $8 per hour, you make $1370 per month. Especially after tax, that's cutting it close but might still be enough to cover rent + food. So if you can make $15 per hour, that should be pretty good.