General

Get to know at least three or four of your neighbours. Be in good terms with them. When shit hits the fan for one of them, help them out. Because eventually shit will hit the fan for you, too, and they're probably geographically closer to you than your family.

Safety

When in doubt, disengage and leave. Even if you need to bullshit your way out. Lies are cheap.

Strangers don't care about you. By default, people approaching you are doing so for their own benefit; doubly so if they claim that it's for your benefit (it isn't).

Drink at home, or at most alongside people whom you know and trust. "A drunkard's arsehole has no owner" - common saying here. I don't smoke weed but this likely applies to weed too.

Every neighbourhood is unsafe at night, unless you know that it's safe.

Talking with cops vary depending on where you live; but at the end of the day "polite, cooperative, succinct" should yield you the least amount of trouble. Lying to cops is usually a bad idea, by the way.

Money

Staple starches (polenta, rice, bread, etc.) are the cheapest to fill your belly with, and should be the basis of your nutrition. You probably consume way more proteins (chickpeas, beans, eggs, meat) than you need, in a pinch it's fine to cut off the amount.

If you're unsure if you need something, then you don't need it.

What I said about strangers not caring about you applies to advertisers, sellers, etc. If they're trying too hard to convince you of something, then odds are that it does not benefit you - disengage and leave, without spending a single cent.

This might sound obvious for some, but wear your old clothes at home. Clothes wear down with usage, keep the good clothes for when you're going out. It's fine to use that shirt full of holes and a permanent stain when the only one seeing it is your cat or your SO, neither will judge you for that.

There's a whole internet of information out there. Before buying something, look for alternatives. You'll be surprised.