Photoshop offers unlimited potential to photographers for editing and retouching that can’t be matched by any other software. The downside to Photoshop is that its wealth of tools and functions can make it quite challenging to master. Even if you have been using Photoshop for years there are almost certainly things that you can still learn.
If you’re pretty new to Photoshop, we highly recommend reading Scott Kelby’s book called The Adobe Photoshop CC Book for Digital Photographers. Scott is a best-selling Photoshop author and you can get his resource on paperback or Kindle.
Here are a few other Photoshop related books:
The Adobe Photoshop CS6 Book for Digital Photographers
Adobe Photoshop CS6 For Photographers
collection of Lightroom tutorials.