Although this video was created using AutoCAD 2008, the same commands and techniques apply to newer versions. View the tutorial that relates to this video.
The video below shows how to set up your drawing before drawing a single line. Set up is important and it's much easier to do it first, rather than to try and patch things up later. Plan your drawing. Figure out your layers and units. How big will the drawing be? Will you draw a lot of similar drawings? Then create a template file (.DWT)
You can view the second part of the project with this video. It will show you how to drawing the floor plan.