If you are looking to get better writing reports, first I will tell you to stop using Report Builder and use SQL Server Data tools (SSDT) or Business Intelligence Development Studio (BIDS) instead.
If you will be at MMS next week there are several presentation on writing reports.
Lastly, if you are looking for a book on the subject then I would look at this one. :-)
http://www.amazon.com/gp/offer-listing/0672337789