If you want to buy a cheap airline ticket, you should bother about it in advance. Besides, not always the cheapest option is convenient and comfortable. When building a complicated route, you should pay attention to the connection points (you may need a transit visa). Often, there is a possibility of stopping on the way, leading to additional costs (a hotel, cab to the hotel). Meta-search of flights can offer options which will involve more than one airline. You should take into account the connecting time between flights. It is more reliable to choose a more extended connection, not less than two hours. Most cheap airline tickets are not subject to change or refund after the payment. You should consider all the peculiarities before pressing the "book" and "pay" buttons.