Maimonides' Principles: The Fundamentals of Jewish Faith

This book goes through the principles of Jewish faith in a clear, concise manner. It even includes some discussion questions that could be potentially helpful for further elucidation of the core principles. The only drawback to buying this book is that it is very short. It is definately worth the money to purchase, but if you can find it in a library, go rent it instead and read it over a few times. $10+shipping for a 100 page book is a teeny bit steep if you are on a budget.

Aryeh Kaplan of blessed memory had a remarkable ability to present complex ideas in a clear and understandable way. Anyone who wishes to deepen in their understanding of the Rambam's thirteen principles of faith would be wise to read this work.