In this After Effects tutorial, we will demystify expressions and make them easy. Software required: After Effects CS5.5.

Introduction and Project Overview
Expressions Do Not Have to Be Scary Math, Coding, or Scripting
Pick Whip Parenting and Expressions
Modifying Our Expressions Values with Hard-coded Values
Adding and Connecting Expression Control Effects for Fast Edits
Accessing Information About Other Layers in Expressions
Using Information from After Effects in Expressions
Getting Properties from the Expression Language Menu
Using Our Current Values or Keyframes to Drive Expressions
Adding Random Movement with the Wiggle Expression
Repeating Animation with Various Loop Expressions
Working with Multi-value Array Properties like Position
Saving an Expression and Its Controls in an Animation Preset
Using Variables to Store Information and Write Cleaner Expressions
Precomping Our Expressions Layers and Creating Copies
Building a Versatile 3D Layer Controller with Expressions