Complete Guide to Creating and Editing PDFs for Free
Editing PDF Files using Web Apps
You can try out lots of PDF editors for free, but sooner or later it's time to pay up or clean off. If you only need occasional PDF editing, consider a couple of free online services:
PDFescape: Includes touchup, merge, form, and markup capabilities. Registration is not required, but allows you to store edited files online.

PDFHammer: Includes security, metadata, page deletion and reordering, and file combining.
Extracting Photos for Free
Want to pull images from a PDF file? Download the freeware Some PDF Images Extract and you can pull JPEG images from PDF files.

A-PDF offers a trial version of its A-PDF Image Extractor. Check out the website to see how you can get a free license.
Conclusion
Before you create a PDF, decide how you want to use it. The way you create it has a lot of impact on its size and features.