My Mom did a lot of baking. I recall one day - years ago - at a holiday gathering, she asked my cousin what made her cookies (chocolate chip, if I recall correctly) so good.  My cousin told her that she sifts her flour. Think about that. Sifting flour would affect how much flour will fill a cup.  Personally, I don't sift flour. But if you are trying to have that perfect cookie, you may want to get a sifter, and try it.  Just a thought. 

I will agree with the Country Crock comment. I don't think i would use it, unless a recipe specifically called for it.

I also hear/ read that you can mix too much.  So pay attention to how long you mix.  Mix just enough to get the dough mixed.

I am no expert but those are my thoughts.