There’s a few obvious ones but my best life hack, as a dude, is regarding shaving razors and cream. Those Gillette things in the UK are damn expensive. They got like 4 razors, super fancy. And the cream too. You don’t need it. I bought a massive bag of the classic razors off of Ebay and moved to the classic shaving soap. Lasts me months.

Eastern Europe tends to be cheaper but you can travel on a budget in most places.

Never heard of fees to enter a city before apart from the ETIAS fee for some countries which is somewhat like the ESTA but cheaper I think.