I like many of Charlie's tips (video links below). Over the longer term, he would recommend an improv class (does your college offer any? Could be a good future elective) and/or Toastmasters. Toastmasters is free--they commonly meet at libraries and schools.

One Simple Tip To Make People Like You


How To Make People Like You - Bruce Lee Charisma Breakdown


Bruce Lee's Insane Charisma


3 Mistakes That Butcher First Impressions


I wouldn't pay--you have done so much self reflection that I think you are going to do just fine!!!