The other thing you can do when starting a new drawing is set the drawing limits which can be found in the menu 'Format/Drawing Limits'

I was always taught to do this by my AutoCAD teacher when I first started out, although I never use it anymore. It basically sets up a drawing area in the form of a rectangle to the size of your choice. So for example if I was going to open a new drawing for the purpose of drawing a house floorpan, I may choose to make the drawing limits 20000,20000 which will give me a drawing area of 20m x 20m. You would do this before you start drawing. 

You don't need to do the above, I just thought it may be worth knowing if you are quite new to using AutoCAD. As always there is often more than one solution for every question.