Be flexible with your times & dates
Avoid bank holidays and peak travel times

On long haul flights, the extra time of going to a destination indirectly can offer fare savings. For example if flying to Cape Town, consider flying via Germany as opposed to direct.

Take a less than obvious airline to your ultimate destination can result in lower fares as airlines offer attractive fares to top up passenger lists. For example, Quantas may offer attractive air fares for passengers wishing to go to Hong Kong.

Sometimes buying a combination of flight & hotel inclusive packages offer savings over just purchasing flights only.

A saturday night stop over also reduces air fares. If you are a frequent traveller between two destinations, consider "back to back" ticketing. For example, if you travel from Heathrow to Nice regularly, then buy a return set of tickets departing from Heathrow and another set of return tickets departing Nice. The trick is to use the outward portion of the Heathrow ticket first to go to Nice. To return back to England, use the outward ticket from the Nice - Heathrow ticket set. Next, when returning back to Nice, use the return portion of the journey originating in Nice. For your final return journey to England, use the return portion of the tickets orginating from Heathrow. The reason that this approach will be cheaper is that by straddling dates you can get a Saturday stopover for each set of tickets.

Book as far as possible into the future as the nearer to the departure date, the more expensive the fares.

Please note that unlike package holidays, you are not insured by ATOL in the event that an airline goes bust; consider using a credit card that offers this protection.