Here is Lynn Allen's annual release of her Tips & Tricks Booklet for AutoCAD 2013. It is a quick snippet of What's New in the latest release. It is definitely a good resource to keep handy when you first dig into the new release, you can go through all of the hot points right away. For anybody that doesn't know about Lynn Allen, here is her Blog where you can find all kinds of information about Autodesk. You can find this one and all of the previous years on my Link bar above under Lynn Allen AutoCAD.
Lynn Allen's Blog
AutoCAD 2013 Tips & Tricks Booklet - Download Here