What is the most logical next event?

How to become a costume designer
Observe and analyze costumes in plays and movies.
While it would be great to attend plays and watch a lot of tv and movies for your personal enjoyment, having a more critical eye will help you start understanding costume design. Make note of the colors of costumes and the materials they're made out of, and practice recognizing factors that influence these decisions.
Time periods and character personalities are just a couple of the different factors that influence costume design. Volunteer at a local theater or film set.