Here’s a quick but very useful Preview tip. Have you ever downloaded a PDF brochure that has a mix of portrait and landscape pages? You can use Tools -> Rotate Left (or Rotate Right) to flip the pages around, but the problem with that command is that it flips
the pages, not just the one you’d like to turn. You can also use the toolbar’s Rotate Left and Rotate Right buttons—you might have to use View -> Customize Toolbar to add them if you haven’t done so already. However, they also rotate the entire document.
So here’s how to make Preview rotate just the currently-displayed page in your PDF: hold down the Option key before selecting Rotate Left or Rotate Right (either the toolbar buttons or the menu commands). With the Option key held down, only the current page will rotate. (If you save the document, it will be saved with the single page rotated.)
This behavior isn’t documented in Preview’s help, which is too bad as it’s quite useful.