EDITING PROGRAM USED: Adobe Photoshop CC (Note: All of the steps used in this tutorial can be accomplished in Photoshop CS3 and up)
After spending a few years in production art, I've become pretty familiar with the art of retouching. I've come across several different methods for prepping product images to be used for both stand-alone presentation and as part of a larger layout. Whatever the end goal is, I've found that starting with these 3 steps is the quickest way to get professional results using Photoshop.