I guess you can kickstart with this book:
MEL Scripting for Maya Animators is the first comprehensive textbook on Maya expressions and the MEL scripting language written especially for the beginning animator or technical director.
The power of MEL for customizing Maya and automating time-consuming tasks has attracted almost all of the top animation and visual effects studios to Maya as their core tool in producing 3D animation. Now, you can learn to master that power even if you have little or no programming experience!
MEL Scripting for Maya Animators begins with an introduction to how Maya functions "under the hood," and proceeds through a series of examples to walk through the capabilities of Maya's expressions and MEL scripting. Next, the book provides an in-depth discussion of the MEL language and how to automate common tasks, and then shows how to build useful graphic user interfaces for your scripts.
Throughout the book's discussion of MEL,
MEL Scripting for Maya Animators discusses the strategies that those new to programming must learn to think about programming problems in such a way that solving them becomes easy. At the same time, the book provides many useful tips and approaches that will be of interest even to those who already have programmed in MEL.
Finally,
MEL Scripting for Maya Animators presents a wide range of specific examples of how MEL and expressions can be used in controlling dynamics, rigging characters, and even building a simple system for crowd behavior.