I am currently working on the creation of a fantasy world for an upcoming fantasy novel. Having surveyed a lot of the literature and websites regarding world creation I found the following most useful:
Creating an Earthlike Planet – this really takes you through most of the process of creating geography, weather and climates. In particular his section on weather is a well explained, simple but invaluable – see his Climate Cookbook.
Also a useful reference for climates are the Koppen classifications, see http://koeppen-geiger.vu-wien.ac.at/
Once you have your climate’s sorted out it’s time to think about how these affect culture. I think this is more difficult, perhaps because there’s no accepted historical interpretation – i.e. it’s quite controversial still – see Jared Diamond’s Guns, Germs and Steel.
Culture creation is probably where you have to read around a lot and figure stuff out for yourself. I found that I had to create language alongside. There are a number of good websites on language creation. I would recommend the following:
The Language Construction Kit – includes all the aspects of language creation you are likely to need. I found that having a core 500 or so words was necessary to cover major nouns, verbs and adjectives.
Ardalambion is a site dedicated to the constructed languages of J.R.R. Tolkien. This is really inspirational and shows what can be done.
I strongly believe creating your own languages for your fantasy world can really enrich them. In my novel I am looking for my characters and cultures to have strong identities that are not based on slightly altered version of medieval earth. We’ll see if I achieve my aim!