WIP
These are some tips for being homeless and/or living outside of this shitty system.
Check out charities, homeless centers, churches etc., they might be able to provide some quick emergency cash.
Begging: possibly the easiest way to get money. Remember, be very nice, not drunk, honesty can help. Try to look like you're new on the street, that someone kicked you out of home, that you just need to buy a bit of food. You may also try to lie with a story like "my wallet was stolen and I need money for a bus to get home". Don't bother people and don't call too much attention, police might come for you.
Small amounts of money can be found near places where people frequently handle cash and wallets, e.g. supermarkets, ATMs, vending machines etc. Look in places where dropped coins might end up (cracks in sidewalk etc.).
Check the vending machines, people sometimes forget to take returned coins.
Some coins may be found in fountains, holy places, shrines etc. as superstitious people leave spare coins there for good luck.
Small jobs: just quickly help someone and ask for small money, get creative. You can lend a help people working on their house. Another idea: near a shop offer an old lady to carry her bags home (don't ask for money yet), while you're doing it talk to her, be nice, friendly, ask about her life (old people are lonely), and once you get to her home very kindly mention that you're homeless and could use some spare money for food.
Along train tacks you can find a lot of metal that falls off trains and is left by maintenance workers, you might collect it and sell it.
You can return carts or beer bottles near supermarkets to get some cash.
You may possibly sell stuff you find in trash to pawn shops.