I found some good links for flex development; these links provide good information for the beginners (also useful at all levels) on how to improve flex development. Primarily focused on how to code.
Below are the links.
Best Practices
http://www.adobe.com/devnet/flex/articles/best_practices_pt1.html
http://www.adobe.com/devnet/flex/articles/best_practices_pt2.html
Coding Conventions
http://opensource.adobe.com/wiki/display/flexsdk/Coding+Conventions
Coding Guidelines
http://blog.dclick.com.br/wp-content/uploads/adobe-flex-coding-guidelines-v12-english.pdf
