Web sites that look different may rely on the same data, or may even be different virtual doorways into the same online travel agency. The better you understand your own travel preferences, the better the chances that you will find what you want. Compare apples and apples. Read all the rules. Understand what you are buying, and from whom, before you buy.
Some tickets are totally nonrefundable and nonchangeable.
If you might have to change your plans, it might be worth paying more for a changeable ticket. Some of the best travel deals you can find online may be with travel agencies you have to e-mail or phone for prices and reservations. Online travel agencies aren't all just robots. Avoid e-tickets as much as possible. Insist on paper tickets whenever they are available, even if they cost a few dollars extra.