There are many ways to open a tune or song. Both specific note choices and methodology are taught in this tutorial with examples in both open G and Double C tuning.
Cathy Fink’s Courses: https://truefire.com/educators/cathy-fink/e4204
Cathy’s TrueFire Channel: https://truefire.com/channels/music-world/h1799
Private Lessons with Cathy: https://truefire.com/private-lessons/cathy-fink/p4204