One hidden gem on the arsenal of Photoshops selection tools, is the Pen Tool. I had been seeing this for quite some time, but I never quite figured out what it was for. Fool that I was, initially, I thought it was for free form writing on a photograph.
Then, I saw this marvellous tutorial on Phlearn.Com on the Pen Tool. It is quite an amazing selection tool, especially when you are making a hard selection.
The selection that you make is stored as a path, and can easily be used as a mask whenever you want to.
What you see below, is the free tutorial, but if you do go to Phlearn.com and buy a tutorial, or take a Pro Subscription, then you get a more detailed tutorial.
Anyway, in the above photograph, I wanted to cut out the pigeon. What I wanted, was to enhance the contrast, and saturation of the waters. I used the Pen tool to cut the pigeon out, then I inverted the mask, and made my adjustments. I did a fair amount of dodging and burning later, for which I used luminosity masks.
In my personal opinion, the pen tool is super for making hard, complex selections. For feathered ones, or even things like mountains (which, may have a hard edge), I would use luminosity masks or other tools like the quick selection tool (etc).
The Pen tool (the keyboard shortcut is ‘P’) is a superb tool. I like it. It takes a bit of getting used to, but have a go!