Getting started with lua?

What would you guys recommend to someone who has some experience with programming (I’ve been programming in C# for maybe 5 years now, and mucked about with Game Maker Language before that), but not enough of lua? Something that doesn’t teach bad practices, gives me a good insight of the syntax, and the general ins and outs of the language. May or may not be targeted specifically for Garry’s Mod.

http://forum.facepunch.com/showthread.php?t=1337945