If you have some time, check out Dynamics GP 2010 Reporting from Packt Publishing. This book will give you some great information with regards to reporting and Dynamics GP.
Whether you are looking to utilize the built in reporting tools such as Smart Lists and Report Writer, or if you are looking to dive a little deeper into SQL, Excel, or Smart List Builder, this book is for you. This book also has a nice breakdown of how the Dynamics GP databases are structured. Between what this book teaches and Victoria Yudin’s list of GP Tables, you should have all the tools you need to get started writing your own reports.