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Flights are usually the largest expense, so attack them first. Use Google Flights to explore flexible date grids, set price alerts, and compare nearby airports. Booking 4–8 weeks out on a Tuesday or Wednesday departure typically yields the lowest fares.
Accommodation costs drop sharply when you move away from hotels. Hostels average $15–$40/night for a private room in most cities. Airbnb, short-term apartment rentals, and house-swapping services (like HomeExchange) can cost 50–70% less than equivalent hotels.
Shoulder season — the weeks just before or after peak tourist season — offers near-identical weather, fewer crowds, and prices that can be 30–50% lower. For Europe, that means May or September instead of July–August.
On the ground, take public transit instead of taxis, eat at markets and local spots away from tourist squares, and use a no-foreign-transaction-fee credit card to avoid the 3% fee most cards charge on every purchase abroad.