Hi there, the best bet is to find a more complicated data source of your own and set about trying to build a document that deals with all the complexities of that data source.
There are a number of resources available out there - the best bet is to Google for them. I wrote a two part blog series on data modelling here:
Also on my blog are a number of links to some of the other great blogs out there.
Remember also, you can always post questions back to QlikCommunities when you hit a problem.
Hope that helps,