You can use VPMAX  (same as double-click within a viewport layout) or VPMIN (same as double-click outside a viewport layout) to switch within model space and paper space tab of a layout.
VPMAX expands the current viewport for editing and VPMIN restores the current layout viewport.
The advantage of using these two commands is that you can pan and zoom while you are in model space, and when you go back to paper space the position and scale of the objects in the layout viewport remain unchanged.
It is useful when you zoom in a viewport on paper space while your viewport borders are not visible and accidentally double click inside the viewport and you cannot double click out.

Below are two standard scale tables for Engineering and Architectural drawings.

To obtain the scale factor of an Engineering drawing scale:

1. Multiply the feet of the desired scale by 12.
2. For example 1″=50′ scale would be 50×12 = Scale Factor 600.

To obtain the scale factor of an Architectural drawing scale:

1. Multiply the denominator of the desired scale by 12.
2. for example 1/4 scale would be 4×12 = Scale Factor 48.

Working with tables in Microsoft Excel is much easier and convenient than the CAD table features in AutoCAD, and there are many ways to use your table or schedules created in Excel to be imported into AutoCAD:
• As a Microsoft Excel worksheet:
The table will look exactly like the Excel spreadsheet you created and changes can be made in Excel by double clicking on the table. In other words, it is an Excel spreadsheet hosted in AutoCAD.
Procedure:
1. Select all the cells that you want to import from Microsoft Excel.
2. Right click, select Copy or simply use Ctrl+C.
3. Open AutoCAD.
4. From the top menu, select “Edit” then “Paste Special” then “Paste” then “Microsoft Office Excel Worksheet”.

• As an AutoCAD Entity:
The Excel table will be converted to an AutoCAD table.
Procedure:
1. Select all the cells that you want to import from Microsoft Excel.
2. Right click, select Copy or simply use Ctrl+C.
3. Open AutoCAD.
From the top menu, select “Edit” then “Paste Special” then “Paste” then “AutoCAD Entities”.

• As an image or picture:
The Excel table will be converted into an image entity.
Procedure:
1. Select all the cells that you want to import from Microsoft Excel.
2. Right click, select Copy or simply use Ctrl+C.
3. Open AutoCAD.
From the top menu, select “Edit” then “Paste Special” then “Paste” then either “Picture (Metafile)” or “Bitmap” or “Image Entity”.

• As a linked Excel table:
The table will be linked to the Excel sheet so that when you make changes in Excel the table will be automatically updated in AutoCAD. This is very useful if many people share one document and constantly need updating.
Procedure:
1. Select all the cells that you want to import from Microsoft Excel.
2. Right click, select Copy or simply use Ctrl+C.
3. Open AutoCAD.
4. From the top menu, select “Edit” then “Paste Special” then “Paste Link” then “Microsoft Office Excel Worksheet”.

• As a linked AutoCAD Entity:
The Excel table will be converted to an AutoCAD table and linked to the Excel sheet, so changes made in Excel can be updated automatically in AutoCAD.
Procedure:
4. Select all the cells that you want to import from Microsoft Excel.
5. Right click, select Copy or simply use Ctrl+C.
6. Open AutoCAD.
5. From the top menu, select “Edit” then “Paste Special” then “Paste Link” then “AutoCAD Entities”.