Trash linked layers:
Command-clicking (PC: Control-clicking) on the Trash icon at the bottom of the Layers palette will delete all the layers that are linked to the active one.
Opacity Shortcut:
You can use a keyboard shortcut to set the opacity for any active layer. To set the opacity down to 40% just press the number 4 on your keyboard. For 80%, press 8, 100% press 0, etc. You can also dial in an exact percentage of opacity (if you can type fast). Just type in both numbers (die: 83 for 83%.)
Hiding Multiple Layers Shortcut:
There's a shortcut for displaying or hiding multiple layers. Just hold the Option key (Alt key on a PC) and click once on the eyeball icon next to layer you want to remain visible. All other layers will instantly be hidden. To view all the hidden layers again, repeat the same steps: Hold the Option (Alt) key and click the eyeball again.
Blend Modes Shortcuts:
You can now select Blend modes for layers with keyboard commands. For example press Shift-Option (PC:Shift-Alt) and the first letter of the blend mode you desire. (For example, to switch the blend mode to Multiply, press Shift-Option-M, or to switch to Color mode press Shift-Option-C.) You can also cycle through the different modes by choosing any selection tool then pressing Shift-+ (plus) or Shift-- (minus).
Hiding and Displaying Layers Shortcut:
Another shortcut to quickly hiding or displaying layers, is the fact that you can click-anddrag your cursor up and down the column of eyeballs, and as you drag, each active layer is hidden.
Shortcut for Moving Multiple Layers to Another Document:
If you have a document open with multiple layers, and you want to move a number of layers to another document, there's a shortcut that will save you from clicking and dragging each individual layer over one by one. In the layers palette, click on any layer that you want to move, then click in the second column (between the eyeball and the layer's name) for every other layer you want to move. This temporarily links them together. When you have them all linked, just click-and-drag the whole lot to your new document.
Move Layers Between Documents:
Another way to move layers between documents is to use the Apply Image feature, found under the Image menu. It enables you to choose any layer, from a pop-up list, and move that layer to a new document (also chosen from a pop-up list.) You can also move the entire image as a flattened file, even if you haven't flatted the file yet.
Preserve Transparency Shortcut:
There is a keyboard shortcut for turning off and on Preserve Transparency. It's the forward slash key (/) on your keyboard.
Putting a Selection Around Everything On A Layer:
There is a shortcut for selecting all the elements on the active layer. Just Command-click (Control-click on a PC) on the Layer's name in the Layers palette. For example, if you have text on a layer, to instantly select all the text, Command-click the layer's name.
Merging Active Layers Shortcut:
There is a keyboard shortcut for merging the active layer with the one below it. This is extremely handy when you've created a drop shadow for text, or an object, and you want to make the shadow and object one layer. Just press Command-E (Control-E on a PC) to Merge Down. Big time saver!
Select One Letter of Text:
If you have text on a layer, but only want to select one letter of text, you have to Render your Type layer, then you can drag a Lasso selection around the letter. Then hold the Command key (Control key on a PC) and press the up arrow key and the down arrow key. This makes the letter a Floating Selection and now you can move the letter any way you'd like (we usually use the Arrow keys on the keyboard to move the selection). When you're done editing this floating selection, press Command-D (Control-D on a PC) to drop the floating selection back down to the layer where you started.
Delete an Active Layer:
There is another way to delete an active layer besides dragging it into the trash. While the layer is active, you can just click-once on the trash can and a dialog box will appear asking you if you want to delete the active layer. Click yes to trash it, no if you made a mistake. To bypass that annoying dialog box, you can Option-click (Alt-click on a PC) the trash can. And yes, if you trash a layer by accident, you can immediately choose Undo Delete Layer from the top of the Edit menu. (Command-Z on a Mac, Control-Z on a PC.)
Covert your Background Layer to a Layer:
To convert your Background Layer to a layer, just double-click on the Background Layer in the Layers palette, and a dialog will appear with the default layer name "Layer 0". However, any white areas of this new layer will remain solid white, and not transparent like a regular layer. Here's a work around for that. If you want the background to be it's own layer, but you want to be able to make the white areas transparent, just make a copy of the background layer. It will be named Background Copy. Then make the original background layer active, select all (Command-A, or Control-A on a PC) and hit delete to erase the original background. Now you background layer is blank (white) and your old background is on its own layer. Now, go back to your Background Copy layer, and use the magic wand tool to select any white area. Then go under the Select menu and choose Similar (this will select all white areas in your image) and then hit Delete to make those areas transparent.
Create a New Adjustment Layer Shortcut:
If you hold the Command key (Control key on a PC) when you click the New Layer icon, you get the dialog box to create a new Adjustment Layer.
Copy Layer Effect to New Layer:
You can copy any layer effect (or set of effects) to a new layer in Photoshop just by dragging the effect label in the Layers palette onto the desired layer thumbnail.
Repositioning the Background layer:
The Background layer is locked by default and cannot be moved. Not only that, you can't unlock it (the lock icon at the top of the Layers palette is grayed out). But you are not out of luck-to move the Background layer, in the Layers palette, double-click on the Background layer and the New Layer dialog box will appear. It will rename your Background layer as Layer 0 and now it will be unlocked and movable.
Applying Styles:
Want to apply a style to a layer using the Styles palette? Just click, drag, and drop that style on your object. The advantage of this "dragging and dropping?" You can drag and drop your style on any object on any layer, not just the current layer.
One-click color-coding:
Want to color-code one of your layers (for easy visual identification) in a snap? Go to the Layers palette, hold the Control key (PC: Right-click), and click on the Eye icon next to the layer you want to color-code. A pop-up menu will appear and you can choose the color you want from this pop-up list.
Don't have a Background Layer? Make One!:
If you are working on a document that does not have a Background Layer and you want to add one, simply create a new blank layer, then go under the Layer menu, under New, and choose Background from Layer.
Shortcut: Duplicate Your layer:
To duplicate your current layer, press Command-J (PC: Control-J).
Float Selection into a Layer::
To "float" any selection and instantly make it its own layer, just press Command-J (Control-J on a PC).
Layers palette shortcuts:
Here are a few quick ways to move layers around in the Layers palette:
To move the top layer down “behind” the layer below-Send Backward: Command-[ (PC: Control-[).
To move the second from the top layer to the top of the layer stack-Bring Forward: Command–] (PC: Control-]).
To move the top layer to the bottom of the stack (above the Background layer)-Send to Back: Shift-Command–[ (PC: Shift-Control-[).
To move the layer above the Background layer to the top of the stack, Bring to Front: Shift-Command-] (PC: Shift-Control-]).
To make the higher layer active: Option-] (PC: Alt-]).
To make the lower layer active: Option-[ (PC: Alt-[).
To make the top layer active: Shift-Option-] (PC: Shift-Alt-]).
To make the Background or lowest layer active: Shift-Option-[ (PC: Shift-Alt-[).
