The only reasonably safe way to carry valuables is near your skin, under several layer of clothing and in a pouch that does not show through your clothes. Keep that pouch with you 24/7, into the shower cubicle with you. A waterproof pouch that ties around your waist is the best, in my view.
Best have some ready to use money and maybe one card in an outer pocket, in a wallet would be good.
That way you do not need to go into your hidden pouch out in the open, so you do not reveal its existence. And if you are pick-pocketed or even stopped and asked for your money at knife point, rare as that is in Europe, you can give them something while the most of your valuables stay hidden.
Any bank or credit card would do for that, one that does not work anymore better than one that does.
But the best way to 'carry' your money is still not have it on you.
If you trust your hostel, you could put most of your money in a sealed envelope and have them put it in their safe for you. But banks are the best, using ATM, as you are likely aware of.