Gaining Experience in Marketing/PR?

I am a Northeastern student majoring in communication currently employed at a 6-month co-op in recruiting. I have previous experience at a summer internship in marketing and a spring internship more focused on general administrative support.

My next co-op will be in January of next year, and my current co-op ends in June. I would like to go into Marketing or PR for my next co-op but am concerned that I don’t have enough relevant experience. Should I be focused on getting a fall internship? Building a portfolio? Taking more relevant classes? What would be the best route to making myself a better candidate for a position in Marketing/PR?

Thanks for your help!