A good way to begin
Start quietly and follow the people near you. If the parish uses an app, printed text, or projected responses, use it for the repeated parts rather than trying to sing every long hymn. Participation grows best when it is steady and reverent.
The first responses to learn are usually Amen, Lord have mercy, Alleluia, and the sign of the cross when the people make it. These responses return often and give a natural way to begin praying with the Church.
Reverent participation
A visitor who does not know the tunes may listen first and join the parts that return often. The goal is prayerful attention before God. Long hymns, seasonal melodies, and deaconal responses can be learned gradually.
If a hymn is unfamiliar, follow the meaning. Listen for mercy, praise, thanksgiving, the Gospel, the Cross, the Resurrection, St. Mary, the saints, and Communion. Singing along is best when it helps attention before God.
It is also fine to stand quietly and learn. In Coptic worship, listening with reverence is already participation, and the repeated responses will become easier as they return from service to service.