A few tips to help get the best of an online search (2016 advice).
Air flights: Always clear the search history on your computer. Most sites use cookies to keep track of whether you've visited before and will boost the prices each time you go back. Change your country of residence to the destination - airlines often have better rates for locals. Skyscanner.net has a price alert feature to notify you when prices change on a specific route and their 'Everywhere' search tool finds the cheapest destinations for your specific date period. [Serena Guen of Suitcase magazine.]
Tuesdays are the cheapest days to book flights, and Fridays are consistently the most expensive. Generally the best fares are advertised 50 days before departure. Flights between 6pm and midnight are usually cheaper. Seatguru.com shows seating charts on all sorts of flights; details include whether a row does not recline, which seat is closest to the loo and where there is extra legroom. [Phil Bloomfield of cheapflights.co.uk]
Feature in Glamour, August 2016