Location > Light > Exposure > Post-Processing
That's simple, isn't it? And yet, the vast majority of photographers (and especially beginner and intermediate) focus on the final step of the workflow. The truth is, no amount of post-processing can create something if the fundamentals aren't there.
Let's see this with examples.
|This works not because of the Post-Processing, but because of the initial conditions|
The photo just above is perhaps one many beginners would see somewhere and ask "how can I replicate this look", implying or even asking what is the proper editing procedure in Photoshop. Well, the reason this can be post-processed like this in the first place is the way the scene was prepared. I used two flashes, one on the left and one directly, with a large diffuser. I then reduced the ambient exposure.
Check this one:
|This would never work as well. It's a boring exposure|
|A very boring, artificial, soul-lacking result|
The procedure in Photoshop is more or less the same. The result is far, far away from the mood the first picture on the top had.
In conclusion, when you see an attractive-looking photo on the net and you suspect there's some "secret" Photoshop procedure that you'd like to replicate, know that it doesn't work that way. You can't just copy the editing part, you must copy the image capturing part as well. Learn about light and exposure, that's the most important step. Then you can think about Photoshopping.
And before everything else, learn about composition!