recently i started to get more into flash,
as a flash / actionscript 2 programmer it interest me to get deeper into the flex / action script 3

here you can find a link for a downloadable pdf which can make your life easier understanding flex concepts.

Things you might learn from the book:

• The basics of doing design work using Flex Builder
• How to customize style and layout using CSS
• How to create and customize themes/skins for your applications
• How to bring design assets into Flex from Fireworks, Illustrator, and Photoshop
• How to effectively bring assets created in Flash into Flex
• How to spice up your design work with useful ActionScript 3.0 techniques
• Several invaluable Flex design techniques from multiple case studies

Flex for Designers