SureStep has a little file that is not always that easy to find, BUT it is a very powerful document for any developer ramping up on or learning Microsoft Dynamics CRM.
The specific file name within SureStep is 1.5.1 Development Standards XRM
Additonally any new and old xRM developer should know about the following resources
Microsoft Dynamics CRM Development Best Practices (available in PartnerSource and MSDN)
Microsoft Dynamics CRM SDK Documentation (available in PartnerSource and in MSDN)
MSDN: Design Guidelines for Class Library Developers, Microsoft Corporation, 2004 (MSDN Library)