How to view and print quality photos on a Mac via email, internet or print

I have been working with iPhoto, Pages and Acrobat on the Mac. Once I create documents in order to send them, I have to reduce the file sizes either within Pages, Preview and/or Adobe Acrobat. However, I am loosing the quality of any images that I use in the document. They all begin to look blurry... How can I keep or retain the quality of my photographs or images when I either print, post (internet) or email? Is it possible to reduce the file or image size without loosing the quality?