Method I :
Editing PDF Files using OpenOffice : I figured the best way to edit a PDF file is to use OpenOffice 3.0.
OpenOffice is an open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more... You can basically consider it as the free version of Microsoft Office. It can be downloaded and used completely free of charge for any purpose, which is great.
In the latest version of OpenOffice -- 3.0 (which is still in Beta stage), a PDF Import Extension allows modifying existing PDF files for which the original source files do not exist anymore. With this extension installed, PDF documents will be imported in Draw and Impress, preserving the layout of the original PDF file and allowing basic editing.
This method is applicable to not only Microsoft Windows user, but also to those who use Linux or Mac.
First, you will need to install OpenOffice 3.0. The free download is available here.
Then download and install the Sun PDF Import Extension. To install an extension to the OpenOffice, simply open one of the OpenOffice application such as the Writer, then go to Tools > Extension Manager, and add the extension there.
After installing the Sun PDF Import Extension, whenever you try to open a PDF file, OppenOffice will automatically import and open it in Draw (one of the OpenOffice application). From there, you will be able to edit the PDF document and then export it back as a PDF after finish editing it.
Method II :
Editing PDF Files With PDF to Word Doc Converter : Another way to edit an existing PDF document is by converting it into Microsoft Word format. Here's a free application capable of converting a PDF into Microsoft Word: Free PDF to Word Doc Converter. The idea is simply converting a PDF file into Words document, edit it, and then convert it back to PDF format. There's a limitation using this method though. If the PDF document that you try to convert contains images, the converter fails to maintain the original layout of the PDF file. Unless you find a better converter, this method applies to PDF documents with only plain text, or with very few images.
There are several commercial PDF Editors out there, such as Foxit PDF Editor (USD99 per license), or the Adobe Acrobat (USD299 per license) that have lots of great features which make PDF editing an extremely easy task. If you need to edit PDF file on a frequent basis, you may consider purchasing these software. But if you are like me who only need it once in a while, and looking for a free PDF Editor, you may try out the method above .