6 Best Practices for J2EE Architecture

6 Best Practices for J2EE Architecture is a nice how to for learning some very important things in J2EE apps:
Lesson 1: Never Shortcut Server-Side Validation
Lesson 2: Security is Not an Add-On
Lesson 3: I18N is Not a Just a Buzzword Anymore
Lesson 4: Avoid Common Mistakes With MVC Presentation
Lesson 5: Don't Be Embarrassed by POJOs
Lesson 6: Data Access Does Not Mandate O/R Mapping

And I think it is a good advice for the Springframework as well, since all the things it advocates are solved by Spring very nicely.