Some great articles on SharePoint best practices have been published on MSDN.

• Best Practices: Common Coding Issues When Using the SharePoint Object Model
• Best Practices: Using Disposable Windows SharePoint Services Objects
• Creating a Windows SharePoint Services 3.0 Web Part Using Visual Studio 2005 Extensions
• Development Tools and Techniques for Working with Code in Windows SharePoint Services 3.0 (Part 1 of 2)
• Development Tools and Techniques for Working with Code in Windows SharePoint Services 3.0 (Part 2 of 2)
• Usage Event Logging in Windows SharePoint Services 3.0
• Working with ASP.NET 2.0 Web Parts and Windows SharePoint Services 3.0