Your trepidation is understandable. Read the Mass before you go so you will have a feel for what is being done and to see the parts which you already know. Many people don’t try to follow the missal the first time, many just watch and pray and that is fine. Allow yourself to enter into the sacred mysteries and enjoy the experience.
My post was from 12 years ago. Since then, I have learned a lot about the Traditional Mass, and have assisted many times at it. I now belong to a parish where it is sometimes offered, as well as the Dominican Rite, which is similar.
I most definitely prefer to assist at the TLM whenever possible, and wish for it to be more widely available.