Do your Photoshop .psd file sizes seem a little large? It may be because of a preference setting that makes Photoshop save a flattened version of your Photoshop image, along with your layered Photoshop file.

Why does Photoshop do this? Because there's a slight possibility you might share this file with someone using Photoshop 2.5 (just like there's a slight possibility that Congress will vote to cut their own salaries), and Photoshop 2.5 didn't support layers, so it can't read your layered document. But because, by default, that flattened version is included in your layered file, guess what2.5 can open the flattened image. What luck! Who cares? I'd rather have smaller file sizes all year long, and if you would too,

go under the Photoshop menu (the Edit menu in Windows), under Preferences, under File Handling, then in the File Compatibility section, for Maximize PSD File Compatibility, change "Ask" to "Never." Think about this one for a minute and you'll wonder why this is turned on by default. Think about it for two minutes and you'll wonder why it's in Photoshop at all. Don't spend too much time on it, or you'll start to wonder who's the poor soul that's stuck on version 2.5.

If you have a multi-layered document and want to turn each layer into its own separate document,

Click File menu, under Scripts, and choose Export Layers to Files.
walla!

USE YOUR LAST SETTINGS AND SAVE TIME

This is a tip that will save you time when you're making tonal adjustments using Levels, Curves, Color Balance, etc. (most anything that appears under the Adjustments menu under the Image menu). When you bring up one of the tonal adjustment dialogs, it always displays its default settings, but if you hold the Option key (PC: Alt key) when choosing it from the Adjustments menu, instead of coming up with the default settings, it will display the last settings you used in that particular dialog. You can also add the Option (PC: Alt) key to the keyboard shortcuts. For example, the shortcut to bring up the Levels dialog is Command-L (PC: Control-L), but if you add Option (PC: Alt) to those keys, the Levels dialog will open with your last-used settings.