Welcome to FlyerTalk! One of the best places to learn about this is to go to the forums of the various airline alliances -- OneWorld, SkyTeam, Star -- they are located further down the FT Miles page. RTW tickets these days are most commonly issued through an alliance or your choices are too limited, and after you pick your alliance (a very limited number of carriers serves some destinations and that restricts your choices), ask the question there.

If you are travelling in economy class, often a combination of consolidator tickets can be noticeably cheaper than buying a RTW fare, although once a consolidator ticket is bought, you usually have to stick to your itinerary as purchased.

Edited to add:

Hah! I beat the moderator to the reply!

[This message has been edited by RichardInSF (edited 08-30-2003).]