I recently came across two excellent papers that give an introduction to star schemas and dimensional modeling. The two papers have a unique anlgle in that they apply a rule based approach to transform transactional ER models to dimensional models.
In the words of the authors:
"An ER model can be transformed into a set of dimensional models by a process of selective subsetting, denormalization, and (optional) summarization. Understanding the relationship between the two types of models can help to bridge the gap between operational system (OLTP) design and data warehouse (OLAP) design. It can also help to resolve the difficult problem of matching supply (operational data sources) and demand (end-user information needs) in data warehouse design. Finally, it results in a more complete dimensional design, which is less dependent on the designer’s ability to choose the right dimensions. "
The two articles give the best explanation of dimensional modeling concepts I have come across anywhere; and the really nice thing is that they give you a tool based on set theory to transform an ER model to a dimensional model.
Another book that has recently caught my eye is Christopher Adamson's book
Other dimensional modeling books you may be interested in: