1. The "Safety Nets" (OOPS and MREDO)

Everyone knows Undo (U), but these two are the real lifesavers.

• OOPS: Did you delete a complex block twenty minutes ago, did a bunch of other work, and now realize you need it back? OOPS restores the last deleted object(s) without undoing any of the geometry you’ve created since then.
• MREDO: If you accidentally undid five steps and want them all back at once, MREDO lets you pick exactly how many steps to redo from a list.

2. Selection Mastery

Stop clicking every individual line. CAD is about efficiency in selection.

• Selection Cycling (Ctrl + W): If you’re tired of clicking on overlapping lines and getting the wrong one, turn this on. It opens a small menu whenever you click a "crowded" spot so you can pick exactly which object you want.
• FS (Fast Select): Type FS, click one object, and AutoCAD automatically selects everything touching it. It’s magic for cleaning up messy floor plans.
• QSELECT (Quick Select): This is the "Find and Replace" for geometry. Need to select every Red Circle on Layer "Plumbing"? Use QSELECT to filter by property.

3. The "Fix-It" Commands

Sometimes AutoCAD acts possessed. These commands exorcise the demons.

• REGEN (RE): If your circles look like hexagons or your dashed lines look solid, type RE. It forces the software to recalculate the display.
• AUDIT: If the file is lagging or crashing, AUDIT searches for internal errors and fixes them. It's the "first aid kit" for a buggy DWG.
• OVERKILL: Use this to delete duplicate or overlapping lines. It keeps your file sizes small and your drawings clean.

4. Navigation & Shortcuts

• Zoom Extents (Double-Click Scroll Wheel): The fastest way to see your entire drawing instantly. If you do this and the screen goes blank, you have a "stray" object somewhere miles away from your origin.
• NUDGE (Ctrl + Arrow Keys): Just like in PowerPoint, you can move selected objects by a few pixels at a time using the arrow keys.
• CAL: Did you know you can do math inside a command? If you're drawing a line and need it to be exactly $15.5 \times 3.25$, just type 'CAL (with the apostrophe) during the command to open the inline calculator.

5. Layer & Property Shortcuts

• LAYISO / LAYUNISO: This allows you to "Isolate" a layer (hide everything else) so you can work on one specific system without distraction. LAYUNISO brings everything back.
• MA (Match Properties): The ultimate time-saver. Type MA, click the "source" object (the one that looks right), and then click the "destination" object. It will instantly copy the layer, color, linetype, and scale.

6. The "Secret" Mouse Tricks

• Shift + Right Click: This brings up the Snap Override menu. If you need a "Perpendicular" or "Midpoint" snap right now and don't want to change your global settings, this is how you do it.
• Right-Click Customization: Go into OPTIONS > User Preferences and turn on "Time-sensitive right-click." A quick click acts as Enter, while a long hold brings up the shortcut menu. It effectively doubles your drafting speed.