To quickly isolate a layer or layers type in the command line: LAYISO. When the AutoCAD cursor asks, select the layer or layers to be isolated. That will automatically lock all layers except the one you have selected. To restore the layer state just type: LAYUNISO.

To edit or create your own line type:
a)    Type LINETYPE in the command line.
b)    When the Linetype manager dialogue comes up, click on the load button (on top right of the menu).
click on file.
c)    Select the browser arrow down to find out the location of your acad.lin file.
d)    Open notepad or notepad++ and browse for the acad.lin file location.
e)    Follow the format below. Once you are done save the file as a .lin extension.

Line type Definition Format

1- Line type name. (You can use underscore but no spaces).
2- Line type description. (It is limited to 47 characters in length).
3- Line type symbol appearance.
4- Length between each symbol.
5- Drawing unit space length before the symbol.
6- Line type symbol.
7- Type of line type (complex).
8- Line type scale
9- Angle of rotation for the line symbol.
10- X-coordinate position.
11- Y-coordinate position.
12-Drawing unit space length after the symbol.

When you have 3D solids and regions drawings you can flat them to 2D views by using the command FLATSHOT. It will create 2D representations of the current view that you have on your screen at execution of the command. The new 2D entities will be generated as a block projected onto the XY plane. You can always modify the block later since it is comprised of 2D geometry.
That is very helpful, especially when you are working with 3D or dxf files. I know a lot of manufacturers have their online catalog cut drawings in 3D format. So that would save you some time and trouble.

When you scale your view in the plotted drawing or paper space, you can use the standard scale list from AutoCAD in the property manager of the viewport instead of using the old method XP factor…. But if you cannot find the scale, do not worry. You can always add or modify the list of scales in the dialogue box. It is really simple: From your AutoCAD command type SCALELISTEDIT. Select the scale from the list to modify. If you need to add more select the “ADD” button. When the add scale dialogue pops up, name your new scale and change the “Drawing units” according to your scale. Hit “OK ” and you are done. Pretty simple!

You can import AutoCAD files into Autodesk Revit and then manipulate it from there as a Revit file or you can xref the file. See this tutorial on how to xref CAD files.

NB: Importing a CAD file will not automatically convert the drawing to 3D.

To import as a link file:

1. Go to the insert tab.
2. Select “link CAD“.
3. Browse for the CAD file that you wish to link.
4. On the positioning tab leave the default position ”Center to Center”. You can also change that to “Origin to Origin”.
5. On the “Place at” tab select the level you want to import the file. For example, level 1or level 2 if you have many levels or floors in your project.
6. Pick your color preference on the “Colors” tab. You can set the link file to show black and white, invert color or the original color.
7. On the Layers tab leave “All” selected, if you want to import all the layers from the file.
8. Leave the “Import units” as Auto-Detect.
9. Select “Open”.

Now that the file is showing in the drawing as a cross reference file. You can also turn on and off layers from Revit as you wish, the same as in AutoCAD.

To import as part of Revit:

1. Go to the insert tab.
2. Select “Import CAD”.
3. Browse for the cad file that you wish to import.
4. On the positioning tab leave the default position ”Center to Center”.
5. On the “Place at” tab select the level you want to import.
6. Pick your color preference on the “Colors” tab.
7. On the Layers tab leave “All” selected, if you want to import all the layers from the file. Otherwise, you can select which layer to import individually. By doing so it will not import any object on unselected layers.
8. Leave the “Import units” as Auto-Detect.
9. Select “Open”.

Once the file is imported you can edit the CAD drawing as a Revit file.

NB: We used Revit MEP 2010 for this tutorial. I believe the steps are similar in Revit MEP 2009. You start from File, Import/Link, CAD formats.

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”.

Follow these steps to add an automatically loading LISP routine to your ACAD STARTUP.

1. Save the LISP file with lsp extension to your C drive in this directory C:\Documents and  Settings\username\Application Data\Autodesk\..your AutoCAD version here..XX\RXX.0\enu\lisp routines folder.
2. Open AutoCad and type “APPLOAD” in the Command line.
3. When the dialogue box pops up, click on
the “contents…” button in the bottom right hand corner (“Startup suite”).
4. In the Startup Suite dialogue box, select the “Add…” button.
5. Browse for your LISP file with .lsp extension that you have saved before.
6. Click Add once you find your lisp file.
7. Close all dialogue boxes and you are done.

The next time you open AutoCAD the lisp routine will automatically load without any command invoke.

Use this command If you need to quickly rotate the crosshairs on the screen at a specific angle so you can draw along any object alignment without having to change The UCS settings nor rotating the view:
In the command line type SNAPANG. When prompted enter the new angle rotation for the crosshairs.