Go to a school that offers Speech Communication as a major. Two great schools that are known for their speech programs are Northwestern & Ithaca. But there are plenty of them out there.
Part of Speech Communication is Communication Criticism, which extends to film criticism, theatre criticism, and other forms of media and arts criticism.
For starters, I recommend you pick up a copy of a book called COMMUNICATION CRITICISM: DISCOVERING YOUR CRITICAL POWERS by Dr. Jodi Cohen. It's a great beginner's book on the basics of thorough art critique.
"Winning a Tony this year is like winning Best Attendance in third grade: no one will care but the winner and their mom."
-Kad
"I have also met him in person, and I find him to be quite funny actually. Arrogant and often misinformed, but still funny."
-bjh2114 (on Michael Riedel)