Which are the Most used Shortcut keys in SolidWorks & Its Function?

Ctrl+X - Cut
Ctrl+C - Copy
Ctrl+V - Edit Paste
L - Line

Default Shortcut Keys of SolidWorks is listed below. In Addition we can customize as per our need and preference.

L Line

Ctrl+1 Front
Ctrl+2 Back
Ctrl+3 Left
Ctrl+4 Right
Ctrl+5 Top
Ctrl+6 Bottom
Ctrl+7 Isometric
Ctrl+8 Normal To
A Command option toggle
C Expand/Collapse Tree
Shift+C Collapse all Items.
E Filter Edges
Ctrl+F Find/Replace
N Next Edge
Ctrl+Q Force Regen
G Magnifying Glass
S Shortcut Bar
V Filter Vertices
F8 Hide/Show Display Pane.
F5 Toggle Selection Filter Toolbar
F6 Toggle Selection Filters

Ctrl+N New
Ctrl+O Open
Ctrl+W Close
Ctrl+S Save
Ctrl+P Print
R Browse Recent Documents
Ctrl+Z Undo
Ctrl+Y Redo
Enter Repeat Last Command
Ctrl+X Cut
Ctrl+C Copy
Ctrl+V Edit Paste
Delete Delete
Ctrl+B Rebuild

Ctrl+R Redraw
SpaceBar Orientation
F Zoom to Fit
F3 Quick Snaps
F11 Full Screen
F9 FeatureManager Tree Area
F10 Toolbars
Ctrl+F1 Task Pane

Crtl B : Rebuilt
Ctrl1 :Front View
''
"
Ctrl7 :Isometric View

C Expand/Collapse Tree
E Filter Edges
V Filter Vertices
X Filter Faces
N Next Edge
F Zoom to Fit
S Shortcut Bar

Don't forget Ctrl+Q : Force Regen

And also don't forget about the mouse to access shortcuts.
When modeling if you click the right mouse button hold it in and move the mouse you can access the shortcut wheel with either 4 or 8 different orientation options.
When in sketch mode doing the same you can quickly access sketch features in the shortcut wheel.

I use a Logitech G700 and they allows to customize the buttons, so I transferred the most important (for me) shortcuts on the additional buttons (9 buttons).
It's a pleasure to work in this manner. It's practically not necessary to use the keyboard for shortcuts any more.