It is a good idea to shoot and edit in the widest colorspace available. Typically, this is Adobe RGB 1998. If you set your camera to this color space, shoot in RAW, and have this as your default colorspace in Photoshop or Elements, it will give you the most possible color information in each shot. However, when it comes time to output to print or web, Adobe RGB 1998 is too wide… your images will look flat and lifeless. Or worse, the colors could shift. So…
For print: When you are done editing your image, go to the Edit menu and select “Convert to Profile…” then select sRGB from the Destination Space popup. Your prints will look much better. Save this image as a copy (flatten it first) and append “_sRGB” to the filename so you remember what it is.
For web/email: In Photoshop CS4, when you select “Save for Web and Devices,” there is now a “Convert to sRGB” checkbox. Make sure this is checked!
For more Photoshop tips and learning, join David Green for Photoshop 201 starting on Thursday, February 11th from 7 to 10pm.