Luke
Did not say which version you've got, but I've started with ACAD10-386. Older than Noah's ARk, but pretty capable for 2D stuff. Backthen I've found that Inside Autocad was a very good help, as it went through starting with drawing a line to making and editing a complete widget.
The most important thing is to know what commands are available. After that, the best thing to do would be to come up with a major 2D project, somewhat comparable to a Space Shuttle complexity, and then try to figure out the ins and outs of each individual option for the commands.
Not really sure why, but there are lots of people who absolutely hate Autocad, but IMHO for 2D stuff you won't find anything faster or more comprehensive.
There are many little things that make your life easy, but short of spending time in a school or with an efficient draftsman, you just have to figure out on your own. You would have to collect an incredible amount of books to get all the little things it does, how it does it, why it does it. I think many people don't really spend the time to get really efficient with it, so perhaps that's the reason for the hatred.
Again, sit down and draw, edit draw edit ..... When you get a WTF moment, try to find it in the online help or in a book and keep at it.
For 3D stuff though, fogget about it.