There's no need to open a file in Preview, use Lion's new-wave Duplicate command (and wait if it's a large file), and then the Save command, to make the copy. Instead, select the file while you're in the Finder and copy it. Switch to Preview and use Command-N to activate the New From Clipboard command. Preview creates a new untitled document from the contents of the Clipboard--even if it's a 200-page PDF file.
4. Paste a copy of a file wherever you need it
You can Option-drag a file or folder in the Finder to make a copy in a new location, but to do that you need both locations accessible at the same time. Instead, select the file in the Finder and copy it. Then open the perhaps deeply nested target folder and paste a copy of the file there. You can copy files in the Finder and paste them elsewhere, too: paste something in a Mail message window, for instance, to attach the file to your message.
5. Move a file with the hidden "Cut and Paste"
There's no Cut command in the Finder's Edit menu. This protects users from cutting a file and then being interrupted (or distracted) before pasting it somewhere, resulting in the loss of the file. There is, however, a cut-and-paste capability in Lion's Finder that lets you move an item without dragging it to its new location.
Select the file or folder, and copy it. Open the window for the new location, and hold Option while you open the Edit menu. Presto! The Paste command now appears as Move To Here (Command-Option-V). Use it, and the copied item disappears from its initial location when it's pasted in the new one.
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