If you don't already subscribe to Ellen's RRS feed or Tip of the month perhaps you should. Click the logo below to go to her site.
Ellen has an ocean of information, all well organized and easy to navigate on her web page. If you want to read more off line she has published several great books including the famous 'AutoCAD Bible' for AutoCAD and LT.
Ellen has free tutorials and some discussion outakes you may find useful. But it's not all AutoCAD. You can also elevate your Powerpoint skills to a new level. Most people can create a basic powerpoint with text and images but there is a ton more under the hood that Ellen can teach you.
Have a look and have fun !