i dont really have pointers to offer.
its just intuition. you just have to know what your doing.
the best i can do is refer you to art and design sites, and you can study up on images.
its all vision-incorporated.
you figure out what to do by remembering what you see.
if you dont know how to use photoshop to a degree that you dont know how to reenact certain effects from memory, then it is a skill you need to develop, or you will fall short, if you lack intuition!

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