I have been travelling extensively for the last few years and buy my airline tickets online itself. I prefer buying through expedia.com, makemytrip.com and ibibo.com. From time to time, I do try some other international sites too but the above sites give me a good price on my tickets most of the time and are user-friendly. The payment gateways are also very secure and the online payment transactions are easy to do. One can even get quick refunds if a transaction has gone wrong.

1. Loyalty Points: If you collect airline miles through your credit card and gold cards, you can convert them into Jet Privilege points in my case and buy tickets directly from them on online travel sites like makemytrip.com
2. Meals: You can choose your preferred meal type instantly while buying online. This can be done with one click. This will add to your ticket base price as meals are chargeable and are not part of the ticket.
3. Refundable: You can take a ticket which has a low refund cost as it is easy to cancel should your plans change in the last minutes. This is, again, refundable at a cost and a price.
4. Seat of Choice: While buying the ticket, one can choose the desired seat one wants on the flight.
5. Travel Insurance: It is best to get your travel insurance at the same time as you book the flight. There is also baggage insurance that one can avail of but this too comes at an extra cost.
6. Excess Baggage: If you are carrying many pieces of baggage and handbags, it makes sense to pay for your excess baggage fee in advance. This will be added to your ticket price.
7. Convenience Fee: While buying a ticket online, one has to pay a little convenience fee too. This is just the service charge one pays for the ease of buying an online air ticket.
8. Online Check-in: One can pre-check-in before the flight through the internet check-in facility and take the proper ticket as one reaches the counter. This is done to speed up check-in procedure and reduce the queues at the airline counters at the airport.

So remember, the list price at which you book your airline ticket will be much lower than the actual price you pay finally with all the value-added services and charges. But it is a one-stop shop for executing your airline travels. One keeps getting reward points and discount coupons from these sites which can be used to buy free tickets or get them at a reduced cost. Make sure you do your bookings at least 2 to 3 months in advance to get the lowest possible prices and optimise your travels to the hilt.