How to know whether to apply early action or regular decision?

I have a list of colleges that I’m applying to, but I’m not sure if I should do early action for a few reasons. I know that my first semester of senior year grades will increase my GPA a bit, which might increase my chances for acceptance. Also, some schools like UW Madison and Purdue for early action don’t release their decisions before the regular decision deadline, so I don’t know if there is a point in doing early action if I don’t know the decision by regular decision deadlines. Any ideas?

I would consider applying early action to schools that give first priority scholarships/aid to those applying early.