30 Days to Learn jQuery
A fantastic (free) video series from Jeffrey Way, of Laracasts, and previously with Envato. I thought I knew jQuery pretty well, but learned a ton of new things, and best practices even in the first few videos. I would highly recommend this series even if you think you already know jQuery.
30 Days to Learn jQuery – tuts+ – free with signup
Options to go through after completing everything above:
Mozilla Developer Network (MDN)
Developing Backbone.js Applications