Today, booking a cheap flight to any corner of the world couldn't be easier.

Booking a cheap flight online is easy, but it can also go wrong. Here are a few insider tips aimed at facilitating the ordering process and avoiding unpleasant surprises.

Book Your Cheap Flight Online as Early as Possible

Not everyone is an early holiday planner, and quite a few people prefer the excitement of last-moment booking. They have to be advised though that the best and cheapest online flight deals can be found a good month or two before the departure date. And these cheap flights sell out really fast, too! Unlike a brick-and-mortar travel agency, an online flight booking site is a very busy place where all the best offers can be sold within hours or sometimes minutes – literally before the reluctant traveler's very eyes!

Flight Insurance is a Must When Booking Cheap Flights Online

Flight insurance costs peanuts, and still some holiday-makers choose to save money on it – often living to regret it. It has very little to do with plane crashes and natural disasters such as hurricanes or overseas volcano eruptions. The most common reasons for missing one's flight are mundane, such as the traveler's change of heart or various travel delays like the taxi stuck in a traffic jam. Without valid flight insurance, online booking offices won't be able to reimburse stingy holiday makers a penny.

Solution: buying a flight insurance may seem like a belt-and-braces precaution to some, but it can save a traveler lots of wonga … better safe than sorry.

When Booking a Flight Online, Double-check the Names of Cities and Airports

When holiday makers book a flight online, they are usually offered a drop-down list of suggested departure and destination airports, and it's a very good idea to double-check them. St Petersburg, Florida or St Petersburg, Russia? Paris, Orly or Paris, Charles de Gaulle? Not only will it save an absent-minded traveler the anxiety of exiting the plane on the wrong side of the globe, it might also save a lot of time and money: some big city airports may offer cheaper flights than others, and the time spent on transfers from one airport to another may become a serious issue.

Solution: when entering departure and destination airports in their respective little search boxes, a holiday maker needs to do some research first to be absolutely sure that's exactly where she intends to go.

Booking Cheap Flights Online: Flexibility is the Key

Being a flexible traveler pays. There's nearly always a cheaper flight offer within a couple of days from the planned departure date. Yes, it might mean rebooking hotel rooms and changing other travel arrangements, so the best advice would be to book hotel rooms and rent a car at the same time as booking the flight.

On certain weekdays, flights to certain destinations may be cheaper while to some others, more expensive: it depends on the airlines operating in the desired destination area. Flights are inevitably cheaper on days of big holidays, like Christmas, when many airplanes carry just a handful of passengers, but just before big holidays, airplanes are packed and prices soar.

Also, in many cases, round-trip flights are dramatically cheaper than one-way tickets. So even if holiday makers plan to book a one-way ticket, they may find it pays to book a round trip, then discard the return ticket. They shouldn't forget though that then they'll have to book return flights separately.

Solution: it always pays to study all the suggested flights the travel site offers, starting from a few days before one's planned departure. There's nearly always a great offer provided the travelers are prepared to make some changes to their holiday schedule.