If you have a Mac running OS X Mountain Lion, the Preview app got some new features that makes handling PDFs a little bit easier. Preview now allows you to insert pages into PDFs without the need for fancy application editing software. You have the option of adding blank pages, scanned pages, or stored pages from documents.
Not sure how? Follow along and we'll show you.
While Preview does contain some nice new features, like adding pages, some PDF tasks are still too extensive and will require use of more extensive software. For that, we would recommend checking out something like PDFPen. Especially if you need the ability to manipulate or add fillable fields to PDFs.