Learning your keyboard shortcuts is a fantastic way to help you speed up your design time. The best part about these shortcuts is that a lot of them apply to a wide range of programs and not just Photoshop. Keep practising and your fingers will find those shortcut keys before you even think about it!

The real time-saver here is that you can change tools without having to drag your cursor back and forth across your screen, and without having to take that hand away from the mouse, as the majority, if not all of the shortcuts, can found and activated using only one hand.

(Note: the first combination shows the Mac shortcut, while the second shows the PC shortcut.)

Create a new document

• Command (Cmd)+ n
• Control (Ctrl) + n

Copy

• Cmd+ c
• Ctrl+ c

Paste

• Cmd+ v
• Ctrl + v

Cut

• Cmd+ x
• Ctrl + x

The above are largely universal shortcuts and you may find they are effective in most of the programs you use on a regular basis, including Word, Excel and your operating system!

Save

• Cmd+ s
• Ctrl + s

Save for Web

• Cmd+ option + shift + s
• Ctrl+ alt + shift + s

Save As

• Cmd + Shift + S
• Ctrl + Shift + S

Open, Close, Quit

• Cmd+ o, Cmd + w, Cmd + q
• Ctrl+ o, Ctrl+ w, Ctrl+ q

Undo, Step backwards

• Cmd+ z, Cmd+ shift + z
• Ctrl+ z, Ctrl+ shift + z

The difference between undo and step backwards is that undo only goes back once, where step backwards goes back to an amount of times determined in your preferences.

Layer Commands

Duplicate a Layer

• Cmd+ j
• Ctrl+ j

Create a New Layer

• Cmd+ shift + n
• Ctrl+ shift + n

Moving layers up, down, top, bottom

• Cmd+ ], Cmd+ [, Cmd+ shift + ], Cmd+ shift + [
• Ctrl+ ], Ctrl+ [, Ctrl + shift + ], Ctrl+ shift + [

This is a very useful shortcut, especially if your document has many layers and you want to move something to the very back.

Merge linked, merge visible

• Cmd+ e, Cmd + shift + e
• Ctrl+ e, Ctrl+ shift+ e

Toolbar

• V = pointer/ move tool
• M = marquee tool
• L = lasso
• W = magic wand
• E = erase tool
• B = brush tool
• P = pen tool
• C = crop tool
• S = clone stamp tool
• D = resets colors to black and white
• X = switches between foreground and background

While it may seem just as easy to move back and forth to the toolbar with your mouse, once you get the hang of the shortcuts you will notice the difference in speed. It is also important to bare in mind that these shortcuts will not work if you ware working within a text box, as they will simply type within the text box. In this instance you will need to return to the toolbar and select whichever tool you are looking for, or, alternatively, select the move tool and then continue to use your shortcut keys.

Fill with Foreground Colour

• Option + delete
• Alt + delete

Fill with Background Colour

• Cmd+ delete
• Ctrl + delete

Brush Size

• up- [ down -  ] (both Mac and PC)

Adjustments

Colour Balance

• Cmd+ B
• Ctrl+ B

Curves

• Cmd+ M
• Ctrl+ M

Hue/Saturation

• Cmd+ U
• Ctrl+ U

Levels

• Cmd+ L
• Ctrl+ L

Inverse Selection

• Cmd+ shift + I
• Ctrl+ shift + I

Image

Image Size

• Cmd + Option + I
• Ctrl + Alt + I

Canvas Size

• Cmd + Option + C
• Ctrl + Alt + C

Other drop-down menu items

Free Transform

• Cmd+ T
• Ctrl + T

Change the size of your image, stretch, enlarge and shrink with a simple key command.

Last Filter

• Cmd+ F
• Ctrl + F

This is really useful if you need to use the same filter on a number of images in a set. It simply applies the filter you used previously on the current image.

Hide/Show Ruler

• Cmd+ R
• Ctrl + R

Hide/Show Guides

• Cmd + ;
• Ctrll + ;

Zoom In

• Cmd + +
• Ctrl + +

Zoom Out

• Cmd  + -
• Ctrl + -

Actual Pixels

• Cmd + Option + 0
• Ctrl + Alt + 0

Toggle (switch) between programs

• Cmd + Tab
• Ctrl + Tab

Custom Shortcuts

If you feel you would like to add further shortcuts for tasks that you complete on a regular basis but are not already set as shortcuts, then you can go and edit your shortcut menu and add more (apple+ option + shift + k). By customising your shortcuts to suit your daily tasks, you can vastly decrease the time you spend in Photoshop completing your regular, potentially repetitive and (hopefully not) boring tasks.

Bare in mind that if you can’t remember a shortcut, take a look on the right hand side of the menu option and you will see  the shortcut there.

I know the list is long, and it may seem daunting at first, but if you make it your mission to learn one or two shortcuts a week, and try and force yourself to use the keyboard shortcuts rather than the your mouse, you will be amazed at how quickly you get used to them, and how much difference they make to your Photoshop experience!

(ref: denisdesigns.com for helping me create a comprehensive list - left some of theirs out and included a few of my own)