Live like you're already poor, reduce all unnecessary spending, adopt an ascetic mindset to support this lifestyle. That way, when a collapse comes you'll be accustomed to living frugally already and you'll have all the money you saved by getting a head start already saved up to get you through rough patches with relative ease.
Now, when I say live like you're poor, I mean do it smart. Don't grocery shop at a gas station, do your necessary purchases in bulk (actually poor people can't or won't, but would be better off if they could.). Don't but the cheapest boots, but rather the best value. But when choosing how many vacations to take, maybe pick camping locally more often than exotic vacations. Eat simple foods, don't order out fancy stuff and get accustomed to such luxuries. Don't automatically buy the latest consumer toy just because it looks fun. Don't move into a nicer apartment just because you got a raise. You get the idea.
At the very least, live like a prudent low-middle-income earner in your country, not like a Bay Area SWE.
Get used to using public transit, if it’s at all an option for you. Going down to being a one-car household instead of two saves us at least 5k EUR per year, even counting the additional cost of two unlimited local transit passes.
Avoid habit-forming conveniences like restaurant delivery, and instead learn how to grocery shop with a list and to cook things you like to eat. If you’re really pressed for time, order your groceries online and pick them up, or get them delivered (that’s an easier thing to back away from if money gets tight than restaurant delivery).
Develop non-consumerist hobbies, where you can get a lot of enjoyment out of little marginal expenditure. I’m partial to fiber arts (free/cheap sheep fleeces I clean with dish soap, then spin and crochet/knit), but there are plenty of relaxing ways to spend time that don’t involve spending much money or being convinced to spend money (like most media consumption - everyone is susceptible to advertising, to some extent)
Now, when I say live like you're poor, I mean do it smart. Don't grocery shop at a gas station, do your necessary purchases in bulk (actually poor people can't or won't, but would be better off if they could.). Don't but the cheapest boots, but rather the best value. But when choosing how many vacations to take, maybe pick camping locally more often than exotic vacations. Eat simple foods, don't order out fancy stuff and get accustomed to such luxuries. Don't automatically buy the latest consumer toy just because it looks fun. Don't move into a nicer apartment just because you got a raise. You get the idea.