Most “how to find cheap flights” articles you will read online were written either by someone who has never paid for their own fare, or by an AI that was trained on the same fifty articles written by the first group. The result is a recycled list of tips, half of which are wrong and half of which were true in 2013.
What follows is the actual booking playbook we use ourselves. Some of it will be familiar; some of it directly contradicts conventional wisdom. All of it has been tested on our own bank accounts.
Incognito mode does almost nothing
The persistent myth: open an incognito or private browsing window and the airline website will show you lower fares because it cannot see your cookies. This was never properly true and is essentially false now. Airline pricing is driven by yield-management algorithms operating on dozens of variables — load factor, fuel cost, competitive pressure, day of week, day of search — and cookie-based personalisation is a tiny rounding error in that calculation.
The one circumstance where incognito helps is when you have been searching the same route repeatedly and the airline’s cached “session” is showing you a slightly stale fare. Clearing cookies or opening a fresh window forces a refresh. That is the entire benefit. The fare itself does not move because you are logged out.
Flexible-date search is the single most useful tool
Skyscanner’s “whole month” view, Google Flights’ calendar grid and Kiwi’s flexible search are all variants of the same idea: instead of pricing a specific date pair, show the cheapest fare across a range. This will routinely reveal that shifting your departure by one day saves £60-£90, particularly on routes where Saturday departures cost a premium that Friday or Sunday do not.
The pattern to watch for: Tuesdays and Wednesdays are usually the cheapest departure days, Saturdays the most expensive, with Sunday and Friday volatile depending on the route. School-holiday windows distort all of this and should be treated as a separate pricing universe.
The “best day to book” myth
You will read that Tuesday afternoon is the cheapest time to book flights. This was based on a piece of US domestic data from a decade ago and was never broadly true. There is no consistent day-of-week pattern in published fares for European routes from the UK. Book when you find a fare you are happy with, in the booking window that suits you, and ignore the day of week entirely.
What is broadly true: the booking-window sweet spot for European short-haul is six to twelve weeks out from departure. Earlier than that you are paying the airline’s confident-they-will-fill-it price; later you are paying the panic-buy price. The exceptions are peak summer (book earlier) and obscure routes with limited capacity (also book earlier).
Error fare watchers
Error fares are real and they still happen. A pricing system glitches, currency conversion misfires, or a fuel surcharge gets omitted, and a long-haul fare appears at a quarter of its normal price. They are usually live for a few hours before someone notices, and they are usually honoured if you book quickly and the airline cannot prove the price was an obvious typo.
The watchers worth subscribing to are Jack’s Flight Club, Holiday Pirates and Secret Flying. None of them are perfect; all of them will occasionally send you a fare that has already been corrected. The trick is to act fast and book directly with the airline, not through an OTA — the OTA can void your booking later if the fare is pulled, whereas a direct-airline ticket is much harder to unwind.
Airport codes versus city codes
Most major cities have a city-level airport code that aggregates all the local airports. Searching LON instead of LHR will return results for Heathrow, Gatwick, Stansted, Luton, City and Southend in one go. PAR covers Charles de Gaulle, Orly and Beauvais. MIL covers Malpensa, Linate and Bergamo. NYC covers JFK, Newark and LaGuardia.
Always search the city code rather than the airport code when you have flexibility about which airport to land at. The fare difference between Charles de Gaulle and Beauvais on the same dates can easily be £40 each way, and the bus from Beauvais to central Paris takes 75 minutes — not catastrophic if the saving is real. The same logic applies to “Brussels” (Brussels South-Charleroi is two hours from Brussels itself, an important caveat), “Stockholm” (Skavsta is 100km from Stockholm) and “Frankfurt” (Hahn is over an hour away).
Hidden-city ticketing: do not
Hidden-city ticketing — booking a longer itinerary with a connection at your actual destination and simply not flying the final leg — is a real way to save money on specific routes. It is also against the terms and conditions of essentially every airline, and they have become much more aggressive about enforcement: voided return tickets, cancelled frequent-flyer accounts, and in extreme cases account-level bans across an entire alliance.
If you must do this — and you should not — only do it on a one-way ticket, never check a bag (it will fly to the final destination without you), and accept that your return on the same record locator is gone. For most ordinary travellers, the saving is not worth the risk.
The baggage maths
This is where the genuine money is on budget carriers. The headline fare is often misleading because the cabin allowance varies wildly between airlines (Jet2 includes a normal cabin bag; Ryanair includes a small under-seat bag and nothing else) and the cost of adding a checked bag varies by route, time and how late you add it.
Standard rule: add the bag at the initial booking, never at the airport. Adding a 23kg checked bag at the gate on a budget carrier can cost over £75 each way — frequently more than the original fare. Adding it at booking is typically £40-£60 return. Our budget airlines guide covers the carrier-by-carrier ranges in more detail.
Multi-stop and open-jaw bookings
Open-jaw tickets — flying into one city and out of another — are usually priced as the sum of two one-ways rather than as a return, which on budget carriers does no harm and on legacy carriers can occasionally help. The genuine value is itinerary flexibility: fly into Naples, train down to Sicily and out of Catania; fly into Krakow, train across to Prague and out from there.
Multi-city searches on Google Flights handle this well. Skyscanner’s interface is less elegant for it but produces similar results. The fare premium over a same-city return is rarely more than 10-15% and the trip improvement is substantial.
What actually works
If we had to compress the entire playbook into five lines: search with flexible dates, search city codes not airport codes, book six to twelve weeks ahead for European short-haul, travel cabin-only or add bags at booking, and subscribe to one error-fare alert service for the occasional spectacular find. Everything else is detail around those five fundamentals.
For specific destination guides showing what the resulting fares actually look like, our ten European city breaks under £150 piece and the Balkans guide are the practical examples.