Sam J. Lucido has a quick, easy method for creating a new layer in AutoCAD.
"Do you ever want to create a layer that is similar to another layer (e.g., similar color, linetype, line weight, etc.)? Open the Layer Properties Manager by typing Layer or LA, and find the layer you would like to duplicate. Select the layer as shown below, and type in the name of your choice."
Notes from Cadalyst Tip Reviewer Brian Benton: This is a great tip — it is simple, yet very useful. Typically if you want to create a new layer, you click the New Layer button, then you set the color, linetype, etc. Many times you are duplicating the settings of another layer, or at least many of the layer's properties. If you select the source layer then click the New Layer button you get the same end results as described in this tip, but you don't have to move your mouse around — just choose and enter.