to me this sounds like you're at the stage where there are just too many options present and unclear experience of a number of topics that leads to more confusion and less clarity on how to go about things.
my borring advice is : mix alot more songs and you will find out for yourself, all that is to know about when to do what and why.

my other piece of advice in pick 1 or 2 mixguys that you "follow" and what to learn from. because "too many chefs in the kitchen ruins the food" idea. different people have differnt philosophy and principles about how you mix a song etc. you dont want to confuse yourself more than necessary.