SETTING THE VIEWPORT SCALE
Setting the viewport scale on your layout sheet used to be a little tricky and made you do some math if you were working in Architectural units. I'll explain the old long way and then the short way to set up a proper scale for your viewport.
The long way
To manually set the scale in a viewport, you first need to double-click within the viewport boundary to activate it. Zoom in to the area you want to show in the viewport and center it up using PAN. If you are working on a Civil or Landscape Architecture drawing, scaling the viewport is pretty simple:
ZOOM (enter) 1/20XP (enter). This will scale the viewport to 1"=20'.
For Architecture drawings, you have to do some math for the conversion of inches to feet. If you want your viewport scaled to 1/4"=1', you have to multiply 1/4 by 1/12, which gives you 1/48. Now, with the viewport active, you can type:
ZOOM (enter) 1/48XP (enter). Your viewport is now scaled to 1/4"=1'.
XP specifies that you want to scale the viewport relative to paperspace units.
The short way
To quickly and easily set your viewport scale, just select (NOT activate) the viewport by clicking it's boundary once. Next, open up your Properties (Ctrl+1 or Right-Click and select Properties if it isn't already open). Under the Misc heading, you will find "Standard scale" on the left. Since the viewport scale hasn't been set, the setting will read "Custom." Click in that field, click the little down arrow to open the selection box and click on the scale you want to use. Deselect your viewport (I use the escape key) and continue with your drawing.